Itsuwa

Itsuwa (五和) is a character introduced in Toaru Majutsu no Index. Seemingly shy girl of the Amakusa-Style Remix of Church at first, she later shows her mettle and effectiveness as an ally of Kamijou Touma.

Etymology
Her name is derived from the real world Itsuwa city in Kyūshū, which was later merged with other towns to form Amakusa City on 2006.

Appearance
Itsuwa is described as a young Japanese girl with black hair (depicted in visual media as purple) that reaches her shoulders. She wears her hair in a bobcut with short fringes. Kamijou Touma upon first meeting her references that she has double eyelids, the first feature he notices on her.

Itsuwa is rather well-endowed but is referred by her Amakusa comrades as hidden. Her clothing consists of things that allows her blend with her surroundings more readily, such as her sleeveless tank top—capris combo or her tank top over sweater with pants that seem to be cut apart. During her mission Avignon, she is forced to wear skimpy clothing because she has nothing else to put on after jumping into the river to save Touma.

Her age is unknown but is still a minor (to drink alcohol), despite being able to pilot a helicopter, drive a motorcycle, and boat, and being referred to as being around the same age as Touma.

Personality
Itsuwa is generally very friendly and warm, though modest. The narrative of the novel has described Itsuwa as "a totally ordinary girl" and she seems to be unintentionally very humble about herself not only in personality but also in appearance, referring herself as "who is only charming with a hint of maturity," apparently allowing her to go to a bar without being interrogated, and that she can not compete with gorgeous women such as Kaori in the looks department, many of the Amakusa support her and assure that she has charm. She is skilled in housework and cooking, the latter being taught by her mother and even enough to impress Tsuchimikado Maika.

She seems to have developed romantic feelings towards Touma, but due to her shyness she has not been able to act on them or convey them to him. She is described as a girl in love. And has even shown to even challenge her Supreme Pontiff, Kanzaki Kaori, when it comes to pursuing Touma, despite only hearing rumors from Saiji. Touma notices that Itsuwa is different from the girls he is usually in contact with, as Itsuwa is not prone to violent outbursts when upset and is more inclined to proper, softer lady-like responses regardless of the situation she is in. She also has been described as someone who matures too late. Her pursuit of her love interest is very innocent and slow, a fact that is mentioned by one of her comrades as her charm regarding her constant use of the "hot towel" technique for Touma. She easily gets flustered by direct contact such as holding hands or being hugged while she drives a motorcycle. Tsuchimikado Motoharu speculates that Itsuwa would dare to wear the Erotic Fallen Angel Maid outift without a second for Touma compared to Kaori, though as shown later, even she is on the fence regarding erotic outfits.

She also easily gets taken away by her emotions, as when she becomes depressed after being unable to help Touma from being beaten by Acqua of the Back, to the point that it took a stern lecturing from Saiji to bring her back to her senses, and later became very enthused in proving Saiji her worth in protecting Touma by preparing her weapon, though scaring Saiji and her other comrades in the process. When down in the dumps, she takes to drinking despite being a minor.

In a mission she becomes serious, and as a member of the Amakusa Church where teamwork is key, she becomes a very reliable ally.

Background
As part of the Amakusa-Style Remix of Church, she most likely resided in Shimabara, Kyushu most of her life with her comrades, and may have been witnessed to the many deeds of her Priestess before she left.

By the time of their introduction into the timeline, they are well known enough for even people like Orsola Aquinas to seek refuge to. However, they still wanted to join Kaori, as is the reason why Saiji wears St. George’s Cross on his shirt, to show that they want to join her. As the focal point of the Saint Destroyer spell, she is most likely present during its creation, in an attempt to truly know of the strengths and weaknesses of Kaori in order for them to stand by her side.

Orsola Aquinas Rescue Arc
Although she is only to implied to have been present during the arc, being one the 52-combat ready Amakusa Christians, in both anime and manga adaptations she is present.

Itsuwa and the rest of the Amakusa Christians were on a pursuit of a woman named Orsola Aquinas of the Roman Catholic Church. Stiyl Magnus, a representative of the Anglican Church, suspected that Saiji and his group have kidnapped Orsola Aquinas and Book of the Law to achieve ultimate power. However, the truth was that they were trying to help her escape, but she could not trust them as they were melee fighters who carried weapons. The Amakusas continued on their pursuit of her and eventually recaptured her in an encounter with Stiyl Magnus, Index and Kamijou Touma, who represent the Anglican Church, and the Agnese Forces led by Agnese Sanctis on a neighborhood just outside Academy City gates. In order to escape their pursuants, Saiji utilized a magical portal located on the nearby Parallel Sweets Park and waited for the exact time they could use the portal to teleport away from the scene. However, the Amakusas' location was spotted by the two forces. Itsuwa and the rest of her comrades are later captured in the ensuing scuffle. Itsuwa and the others are later kept in the Church of Orsola.

After Saiji is freed by Touma and company after the Roman Catholic Church forces revealed their true nature, Saiji goes on to save Itsuwa and the others while Touma faces the Agnese Forces on hiw own. She later gets invovled in the Battle of the Church of Orsola. Saiji later has He later has his comrades place Stiyl's rune cards all over the Church of Orsola grounds to create a large magic array as so Stiyl can summon Innocentius. It was part of Touma's plan and he later discovers the nuns being cowed by Innocentius as well as their leader being cornered. Saiji later witness Agnese Sanctis' defeat at the hands of Kamijou Touma.

As part of Laura Stuart's plan to tether Kanzaki Kaori's loyalty, she allows the Amakusa Christians to join the Anglican Church. Itsuwa and the rest then began living in London's Japantown. There, Itsuwa does work for a bento shop on the first floor of the apartment complex she resides in when not in missions.

La Regina del Mare Adriatico Arc
When first introduced into the series, she appears alongside other members of the Amakusa-Style Remix of Church to aid in Orsola properly move her wares from her house in Chioggia before permanently staying in London as part of the Anglican Church. This is when she properly meets Touma in person for the very first time, after hearing from the other members of the church of Touma's prowess, facing 250 battle nuns on his own before back-up arrived from the Amakusa Church, Stiyl] and Index. All of the Amakusa Christians seem to show respect to Touma after hearing that he has also fought Kaori, seen her totally naked, received her Nanasen and has somehow managed to walk away from said incidents alive. She takes an immediate liking to him and starts trying to get closer to him by giving him a hot towel. However, every time she sees Touma might be in need of the usage of a towel or a napkin, her eyes shine in a strange way and she blushes strongly upon what she perceives as a "chance" to carry on with her "getting close to him" strategy; a usual comic foil of the series is Touma obtaining a napkin from someone else when Itsuwa was ready to hand him one. This fact of being unable to progress with Touma is noted by one of her Amakusa comradres as part of her charm.

As part of the Amakusa Church, she aids Touma and company in saving Agnese Sanctis and her Agnese Forces, despite being former enemies, indicating that they are faithfully following their Priestess' example, that they should always aid all those in need, as well as stop Biagio Busoni and his Queen's Fleet from destroying the science side. In the Battle of the Adriatic Sea, she boards of the Queen's Fleet ice ships and fight off the former Agnese Forces as Touma, Orsola, and Index go to the La Regina del Mare Adriatico to stop Biagio and save Agnese.

Anglican Church–Russian Orthodox Church Prewar Conference
Apparently a few days before the two great Churches come together for a meeting for the War, the Knight Leader goes towards Japantown where the Amakusa live and asked for Kaori, wanting to invite her to a dance. However, Saiji who was there states to him that it wasn’t going to happen and they got into a heated argument. In the middle of all this, Saiji shooed the Knight Leader away with his hands telling him that Kaori prefers to lead younger guys than to be led by older guys and then mentioned that Kaori has already someone she loves in Academy City. Itsuwa is also present, telling herself to do her best.

Document of Constantine Arc
The Amakusa Christians is requested by the Anglican Church to investigate the leylines and other magical properties of the land in France after a series of riots erupts around the world against Academy City. The 52 combat-ready members of the Amakusa Church go towards major cities in France, with Itsuwa in charge of Avignon. Her original task was simply to investigate, and once she has enough information she is supposed to contact Saiji so that a large team can gather and break in at once. She later becomes suspicious of the Palace of the Popes, the Palais des Papes, but decides to gather more information before gathering her comrades.

After Tsuchimikado Motoharu and Kamijou Touma is recruited by Oyafune Monaka to stop the riots, they travel to Avignon and parachute towards the city in order not to draw the Roman Catholic Church if they try to land the plane on French ground. Touma almost faints after being strangled by his own parachute strings after parachuting from their plane. Itsuwa rescues him before he drowns. It is discovered that Amakusa Christians are gathering info in France on what is causing the disturbance, and Itsuwa finds Touma seemingly by pure coincidence as shown by her not knowing about why Motoharu and Touma are there. She and Touma go to a nearby cafe to plan before making a move. Itsuwa explains how popes used to visit Avignon a couple of centuries ago, when France and the Vatican had a dispute and France emerged the victor, as well as her suspicions on the Palais des Papes for where the Document of Constantine is being used as well as the pipeline that allows it to be used in Avignon in the first place running from the city back to the Vatican created back during the Avignon Papacy in order to facilitate rituals that can only be done in the Papal State (before the Vatican was established) without needing to leave Avignon.

The two are spotted by an angry mob before they can actually plan anything out. It seems that their animosity towards Touma comes after seeing him drop out of the plane, making Touma logically conclude that the Roman Catholic Church forces in the Palais des Papes are using the C-Document to hunt them down. Touma and Itsuwa start moving toward Palais des Papes, needing to destroy the C-Document before the magicians could escape as they could use it again. While dodging the mob to get there, Tsuchimikado Motoharu contacts them. It is revealed that he too is on his way to Palais des Papes, but a wall of angry mobsters block his path. Touma reveals to Motoharu regarding his knowledge of the Palais des Papes. There, he tells Touma and Itsuwa to sever it, banking on getting to the palace and calming down the rioters and immediately going to the palace before the magicians could leave, Touma and Itsuwa decide to alter the magical pipeline connecting Vatican and Avignon which allows the document to activate instead. This pipeline is basically a flow of energy that runs throughout the globe, and either Itsuwa or Tsuchimikado is needed to alter its path away from Avignon. The two end up at one of the city's many museums. Touma thinks about breaking the link using his Imagine Breaker but is told by Motoharu that it might not work on the natural mana flow of the land, as there are exceptions to what the Imagine Breaker can negate.

As Itsuwa prepares to user her Amakusa brand of magic to alter the ley line, she hesitates after realizing has to use a pair of panties for it, though quickly made up her mind. After lining up the magic circle, an arpeture appears on the floor, and Itsuwa merely dips her Friulian Spear into it, and as she is about to turn her spear to alter the ley line. Terra of the Left, one of the God's Right Seat attacks them, destroying a wall in the process. The attack leaves Itsuwa's Friulian spear broken, which she immediately replaces. Terra of the Left appears before them and attacks Touma, and is surprised on how he manages to negate his flour guillotine. As Itsuwa and Touma become wary of him, Touma asks for Terra of the Left's identity, to which he easily says as he gathers his flour back into a form of a blade. The fight moves to the outside, and here Terra of the Left shows the wanton destruction his blade has upon the streets. Touma intended to draw Terra's attack and Itsuwa would get in range to attack him. Here, Terra realizes that he is dealing with the Imagine Breaker, the one that defeated Vento of the Front. He swings the blade towards Touma who lets out his hand, but Itsuwa intercepts the blows of the blade herself. She tries to strike Terra of the Left down but he is fast enough to swing his blade towards her and buy him enough time to attack again. Suddenly, he notices steel wires surrounding him, and Itsuwa uses her Seven Blades of the Seven Teachings technique to cut him down. There however, Terra of the Left uses his "Precedence", his Execution of Light spell for the first time in front of them, making him immune to the wires. Initially shocked, Itsuwa nonetheless tries to stab Terra of the Left again, but uses his "Precedence" spell to disappear in to phase through the wall behind him, making her miss. Using Precedence again, he destroys the wall with his guillotine, forcing Itsuwa to dodge. Seeing this, he tries to attack her in her vulnerable position, but Touma intervenes, and his blade is once again destroyed. Using his spell again, he gathered the blade back, and used it to strike down the wall on them, forcing Touma to take Itsuwa to avoid the falling debris.

Terra of the Left states his disappointment on Touma's Imagine Breaker, concluding that Touma only won against Vento of the Front after Touma destroyed her Divine Punishment, summoned the "fallen angel", and brought out a strange realm to pressure on her. Here, Touma realizes that a member of God's Right Seat who is on the same level as Vento would not attack with just a blade, and became disturbed by him. Seeing this, Terra of the Left mocks him, and states to him that he should at least allow him to enjoy their little situation a but more even if what he is facing is the best Touma has. Then, Touma and Itsuwa attacked simultaneously. Using his spell, Terra stopped the movements of Itsuwa's spear, stopping it in mid air. Touma attacks but Terra is faster, and the blade hits Touma's body but it does not cut him as he expected though he is still hurt by it. Touma then punched the guillotine that hit him and it is once again destroyed, causing Touma to think more about the implications of Terra's spell. As he regathers his flour, Itsuwa states that Terra's power is Precedence, to which Terra explains to her the symbolism used for his blade, the mythology associated with Christ's death, and it, being the reason why he has the Precedence spell. It is based on the secret ceremonies required to complete the story of the Son of God is the alteration of the order of precedence, the Execution of Light, and flour he shapes into a blade as medium is a by-product. After his explanation, he is confident that them despite knowing of how his abilities origins and mechanics, he can still defeat, and he was right. He then gives them time to make a up a plan for his entertainment.

Suddenly, Tsuchimikado Motoharu arrives and shoots an magical origami figure at him, though Terra simply uses his Precedence spell to make it bounce off him, landing the thing near Itsuwa. Motoharu declares that he has cornered Terra of the Left now. He takes the handgun he took from Oyafune Monako a while back, and as he shot Terra, he quickly predicts what Terra was going to say for his spell. Motoharu, confident that he can beat Terra, boasts that he can beat him and takes out a black origami figure, and Terra can only watch in silence. As Itsuwa relates to Touma that Motoharu wants them to go to the Palais des Papis at the same time Terra and Motoharu starts making their move, explosions ring out, the invasion of Avignon has begun.

Academy City invasion of Avignon
Although annoyed that his battle with Motoharu was interrupted, as he wanted more battlefield data for his precedence spell, Terra of the Left quickly escapes them during the attack by Academy City's HsPS-15 Powered Suits. Seeing that Academy City is simply attacking civilians, though non-lethally, dumbstrucks Touma, and reminds him of why Monaka may have asked her to help stop the protests in the first place. Itsuwa tries to check on Touma asking him if he is all right as she helps her out. Motoharu calls out to Touma and tells her to go to Palais des Papes. Touma asks if it's all right to leave without doing anything seeing as it is Academy City that is attacking, to which Motoharu says that going after Terra comes first, and that the Academy City forces are after the Document of Constantine as well. Motoharu tells Touma and Itsuwa to go to the palace, seeing it as the only chance to destroy the document. Motoharu then says that he will stop the Academy City forces and negotiate with them. Annoyed, Touma and Itsuwa is forced to go to Palais dep Papes, leaving Motoharu behind.

When Touma and Itsuwa reach the empty Palais des Papes, he contacts Misaka Mikoto regarding current events with Academy City, Terra throws an HsPs-15 Powerd Suit towards the building, destroying a wall and knocking his phone out of his hands. There, he comes upon Touma and Itsuwa again, dismayed at the attacks stopping the spell, and says that are retreat would be the best option. Touma and Itsuwa obviously doesn't want him to leave, but mocks at their powerlessness, challenging them to stop him.

There battle begins as HsB-02 planes use their Earth Blades to melt the ground around Avignon. They ignore the attacks going on outside and do battle. Touma and Itsuwa move first but Terra quickly uses his spell that forces Itsuwa to help Touma dodge Terra's attack, which tears apart the palace. Itsuwa then manages to strike Terra but he used his spell to make blades not work on his skin. The force of the attack knocks Itsuwa down taking Touma with her. She is hurt by the debris and Terra takes advantage of that fact, he makes flour have a higher precedence to human skin, swinging down his blade towards her. However, manages to destroy it before it reaches her. He tries again and Itsuwa just pushes Touma aside, making Terra miss. Terra mocks her for getting in Touma's way. Itsuwa agrees, but says to Terra on how he has revealed his fatal weakness. Terra uses his Precedence again to make the ceiling collapse with his flour, forcing Itsuwa to hurriedly wedge her spear between the ceiling and floor. Without her weapon Terra attacks her, hitting her body and knocking her out. The ceiling then returns to normal and Terra gloats over his victory.

For much of the fight between Touma and Terra, Itsuwa is unconscious and is unaware of Terra revealing that Touma has lost his memories. Later, after Touma has already defeated Terra and is interrogating him about what exactly Imagine Breaker is, an attack from an HsB-02 blows the two of them away. Itsuwa regains consciousness and finds Touma again knocked out and injured by the explosions caused by the HsB-02. Parts of the room are seen to have actually melted due to the sheer amount of heat and are covered in steam. Itsuwa overhears Accelerator speaking just as she is about to start tending to Touma. Accelerator is speaking with one of the higher ups of Academy City over the phone, telling them to send troops to come search for Terra's corpse and run DNA tests to see if he's really dead. She stays hidden, not knowing if Accelerator is friend or foe, steam giving her enough cover so as to not be seen. Accelerator leaves soon after to a deeper part of the palace. She states that she finds Accelerator, who can stand in flames like that, even more terrifying than Terra.

Acqua of the Back Arc
Two days before the start of the arc, the Anglican Church and Academy City both receive letters from Acqua of the Back threatening that he will crush Touma, and warns them that if they intend to stop him, then they must prepare to use all their power. Moreover, he sends the corpse of Terra of the Left to the Anglican Church prove the letters' authenticity, and Itsuwa is then called to confirm Terra of the Left's identity, having fought her in Avignon. Because of this threat, the Amakusa Christians were sent to protect Touma, since they can be used as a scapegoat when things get bad and that since they're based on Japan it gives them a geographical advantage.

As a set-up by the Amakusa Christians to get Itsuwa to become closer with Touma, Itsuwa is tasked to be Touma's bodyguard. Itsuwa is first seen outside of Touma's school and discovers much to her surpise, a large man chasing Touma. Mistaking him to be Acqua of the Back as she has never seen him before, she tries to attack him. The chase is brought to an end, and Saigo is apparently forced into a retreat due to "health" reasons, much to Touma's relief, allowing him get lunch. After class, Touma speaks to a saddened Itsuwa, embarassed by her mistake. Itsuwa asks Touma if he knows who Acqua of the Back is, to which he informs her that he has met him back in September 30. Itsuwa later tells Touma that Acqua's target is him, saying that the Anglican Church and Academy City has received letters of challenge. Touma is doubtful with Acqua of the Back going after him after Vento of the Front telling him on how the Pope required many documents to have people attack Academy City. Itsuwa points out that it is because that Touma had a hand in stopping their nefarious plots that they have Acqua of the Back after him. Itsuwa notes that the British Library is checking on his history, and though there is not much to go on, concludes that he must be powerful to be included in God's Right Seat and has the strength of a Saint, and wishes for Kaori to aid them. Itsuwa points out that fighting in Academy City should be a great advantage, as both Vento of the Front and Terra of the Left gave them opportunity to fight back due to interference of science. Still though, Touma says that he doubts that it would be that simple. Itsuwa tries to reply but can only mince words and in a flustered states says that she will be protecting him as they have been given orders by the Anglican Church. Touma asks again why Itsuwa is there with him, as he does not believe what he has heard. She then reiterates that she is his bodyguard.

Meanwhile, the Amakusa Christians bored with Itsuwa's slow pace in getting together with Touma plans to have him plant his head plant on Itsuwa's breasts. He is successful, but he manages to catch the attention of Misaka Mikoto, irate on what had happened to Touma. Saiji and the other later leave quickly without a trace. Meanwhile, Itsuwa doesn't know what to do, she is flustered and tries to rub the part of Touma's head. Mikoto dashes towards Touma and attacks him using her Electromaster powers. In order to fulfil her job, Itsuwa started to assemble her spear, and in order to stop her, Kamijou hugged her, leading to Mikoto becoming angry again, forcing Touma run around Academy City.

Itsuwa arrives in Touma's dormitory, leading to Index questioning why she is there. Itsuwa tries to explain to Index regarding God's Right Seat but is told to be quite about it by Touma around in Index as he doesn't want her involved. Itsuwa understands but is flustered after Touma took her away by the wrist. As Index becomes incenssed, Itsuwa notices Sphynx, and gives it high-class catfood as a present. Touma notices the various foodstuffs in Itsuwa's bag, to which she claims is that despite her being a bodyguard, she shouldn't just eat and drink for free, telling Touma to entrust her with the housework. The atmosphere completely changes as Touma becomes enthusiastic, much to Index's surprise. He shows Itsuwa the wok for her to use Itsuwa's presence greatly lightens Touma's mood. Itsuwa then begins cooking much to Index's excitement, and tries to bother Itsuwa for it. Having none of it, Touma shouts at Index to "stop ruining a man's dream," and tells Index to follow Itsuwa's example. He forces Index to clean the bathroom while they wait for Itsuwa to finish her cooking. As Touma begins to do some housework himself, there Tsuchimikado Maika smells the scrumptious smell of the miso soup. Maika is able to automatically pinpoint the special ingredients Itsuwa made, much to her bewilderment, and acknowledges Itsuwa's skill. Seeing to one up her, she returns to Motoharu's room and throws away the cream stew she prepared for his dinner, in order for her to make a much better miso soup. Itsuwa hears Motoharu's cries, and recognizes it as from the incident in Avignon but is unable to confirm it.

After dinner, Itsuwa suggests going to School District 22 for a bath after Index destroys the bathtub in her attempt to clean it. With the last bus already leaving, Itsuwa takes Touma and Index using a rented motorcycle with a sidecar, leaving Sphynx with an expensive scratchboard to play with. With Itsuwa speeding, Touma is forced to grab Itsuwa's waist even tighter as he is riding behind her, making her happy. They later enter the district to which Itsuwa relates to Touma on her surprising knowledge with the City. There, Itsuwa bathes with Index and comes upon Misaka Mikoto. Mikoto becomes noisy in the bath but is promptly scolded by Index. Mikoto recognizes Itsuwa as the "girl who got hugged by that idiot because of some strange soccer ball," making Itsuwa embarassed and ebb into the water. Mikoto starts to wonder if the two know about his memory loss and while pondering about the issue again, she faints in the bath and Itsuwa and Index is forced to call the staff to have her resuscitated.

Leaving Index back in the bathhouse who wanted to taste some of its food there, Itsuwa accompanies Touma for a walk. Here, she and Touma talk about the Amakusa and their life in England, and later moves to Itsuwa and Kaori's clothing. Itsuwa then talks using the metaphor of Vega and Altair (Orihime and Hikoboshi respectively, the star-crossed lovers of the Tanabata) to describe her relationship with Touma, not being able to see him, though Touma doesn't understand. Here, they are unaware that Acqua of the Back has appeared before the Amakusa Christians and utterly defeated them. The two continue to talk, with the topic flowing towards Acqua of the Back, God's Right Seat, and the role of the Amakusa Christians in protecting them. They later move to a bridge, and after Itsuwa blushes at the thought of them being alone together, they note their queer situation. There is literally nobody other than the two of them. And there came steps from the darkness and it showed Acqua of the Back. He reminds them of his warning, but since they've chosen this path he tells them that he will use all of his strength to crush them. Acqua of the Back says to him that he has come to crush him, the reason for all the unrest in the world. Touma calls him out on this, and references what they did to Avignong. But Acqua would not yield, and points that what happened there only happened because of Touma and his Imagine Breaker. He then tells Touma to hand over his right hand if he wants him to spare his life. Itsuwa asks about the Amakusa Christian, to which Acqua says that he did not kill them for what he wants is not them. Despite Touma and Itsuwa's concentration, they are caught unawares. Acqua sends Itsuwa flying with a single hit, allowing him to attack Touma with his giant mace that he summoned. Fortunately, Itsuwa somehow flings her bag between them, sparing Touma for the moment from the large mace despite the debris hitting him. But the sheer power of the blow flings Touma high up and then hitting the metal frame of the bridge, making him fall. Itsuwa hastily assembles her Friulian Spear, and she prepares to fight despite being damaged from the previous attack. Acqua of the Back points out the folly of challenging the man whom her entire group couldn't beat, but Itsuwa would not yield. Seeing this, Touma tries to stand but is unable to as Itsuwa and Acqua fight in high speed. But it is quickly over as it had begun, and Itsuwa is hit with the mace and then tossed towards Touma, hitting him. Touma understands the situation, that he could not hope to match against Acqua even after he fought Vento of the Front and Terra of the Left. Acqua of the Back once again asks for his right hand, but Touma doesn't cooperate, prompting Acqua to attack him again. Itsuwa regains consciousness after Acqua of the Back pummels Touma to the point of drawing blood. Touma appears before a bloody mess. She is horrified by this, at which point Acqua notices her, telling her to move or she'll be caught by the tremendous power of his attack on Touma. Itsuwa breaks down and desperately tries to heal Touma in spite of his right hand. But it is vain due to the Imagine Breaker, and Itsuwa can only cry. Acqua of the Back tells her that it is enough, and steps on her back, silencing her cries and moans. As Acqua tries to come towards Touma, a screaming Itsuwa raises up her arms against Acqua again, trying to protect Touma. Acqua sighs as he and Itsuwa prepare for the inevitable conclusion of their clash. However, before Acqua can strike him down, Touma once again stands by her side. He thanks Itsuwa for the healing magic despite her knowing it did not work, and in her shock, cannot stop him from going towards Acqua of the Back, to protect her. To save Itsuwa, Touma alone stand against Acqua, impressing him. Acqua of the Back deals a horrendous blow upon Kamijou Touma, but does not kill. Touma is hung upon the mace. Acqua of the Back smiles at Touma's courage, and tells Itsuwa that he is giving them one day more. He tells her that he will give them one more day to choose whether or not to give Touma's right hand, and if they did, he will spare their life. Afterwards, Acqua swings his mace that had Touma on it, flinging from the bridge and into the cold water at high speed, and finally sinking after bouncing from it several times. Without confirming whether his target is dead, Acqua turns his back on Itsuwa for one day more.

Touma is later taken into School District 22 hospital, and where the Amakusa gather once again. After hearing the doctor's diagnosis in a hospital in School District 22, Saiji says that they should at least apologize to him, but the doctor vetoes the thought. Powerless, the Amakusa can only regret that they have failed to protect Touma. Saiji sees Itsuwa sitting in the corner sulking and dwelling on her own failure of protecting Touma, to which an irritated Saiji raised her and told her on how Touma could've protected a woman such as her. Before Itsuwa could raise her hand on him in anger, Saiji throws her down, and tells that Acqua of the Back will come back and asks if they should continue continue sulking or stand up and confront Acqua of the Back and defend Touma. He tells Itsuwa that if she wants to apologize to Touma, she must make it so that she is someone who was worth protected by him. He asks his comrades if there is anyone who feels the same way as Itsuwa before as so he could wake them up. Predictably, no one responds, and they once again prepares to take on Acqua of the Back.

They later have the 50-strong Amakusa Christians in an alleyway in School District 22, awaiting the intelligence from the Anglican Church regarding Acqua of the Back. Saiji reports to his comrades that Acqua of the Back is currently fighting unmanned robots, and that they should prepare first before challenging him. As the Amakusa prepares for their battle against Acqua of the Back, Saiji turns to find Itsuwa, finding out that she is intensively strengethening her weapon beyond normal. This makes both Saiji and Ushibuka both unnerved, with the former thinking that he went overboard with her. Orsola Aquinas later calls Saiji to inform him of what they learned of Acqua of the Back, and though they learn no weakness and discover that Acqua of the Back is more powerful than they thought, Saiji and the others are still determined to protect Touma from him. Itsuwa was the one who contended against Acqua of the Back directly, while the rest of the Amakusa Christians support her by continuously changing the focal point, it was a spell that increases visual activity and mobility, allowing for Itsuwa to match up to Acqua of the Back's speed. After he begins catching up to Itsuwa, the Amakusa Christians the planted wires around him, though his strength allowed him to resist a little, they eventually activated the spell, and Acqua of the Back's body is engulfed in a red mist prison that explodes from within. And yet Acqua of the Back continues persisting, referring to his Divine Mother's Worship which allows punishment upon him to be weakened, basically making their attacks meaningless. Acqua of the Back then tries to attack, forcing the Amakusa Christians to retreat. They later regroup 300 meters away from the metal bridge where they fought Acqua of the Back. With Acqua of the Back always breaking their formation, Saiji concludes that they should better use the weakness of the Saints, since they have properties similar to the Son of God, then they will be weak to things that have similar properties to those that have excuted him. Feeling Acqua of the Back coming, Saiji tells his comrades to get into position, they create an entrace to the space between the third and fourth level, a hydroelectric turbine power plant. Saiji and the others set-up wires and trap spells down below in order to delay him long enough for them to set-up their counter against him. With Acqua of the Back's arrival, Itsuwa becomes the focal point of their formation once again. Here, Itsuwa discovers that despite being a member of God's Right Seat, he is still able to use normal spells due to his Divine Mother's Worship. Thus, being aligned to water, Itsuwa runs for her life as everything around her is a weapon for Acqua of the Back. Itsuwa is later blown down the screen that acts as the 4th level's sky. Both draw their weapons, and Acqua of the Back prepares to end the battle, however, the other Amakusa Christians finally arrive through the entrances. Battered and injured, the Amakusa Christians face down Acqua of the Back.

While Itsuwa fights Acqua of the Back directly, other members attack him in every direction, however, they are still no match for his impeccable power, blowing them away. Acqua continues his attack and swings down upon Itsuwa, who barely escapes by using her sweater as a scapegoat. Itsuwa trades blows with Acqua of the Back, but the both of them know that she is getting slower. The other members support her by attacking once again in all angles, but they are once again blown away. While Acqua of the Back is busy, Saiji calls out to Itsuwa if the spell is ready yet, but their conversation is quickly interrupted after as Acqua of the Back attacks him. Saiji manages to block the strike but is still blown away by him. Acqua of the Back presses on with the offensive, slowly sapping Itsuwa's strength and endurance blow by blow they trade. However, as he moves, he soon discovers that the spell that allows him to glide and move in extreme speeds have been mixed in with some substance by the Amakusa Christians, moreover, the shockwaves brought about by this disruption rips apart the screen that he is standing on. With this gap, Itsuwa smiles and charges forward with her spear, seeing this, Acqua of the Back dodges for the first time in their battle. He jumps up, but that is enough for Itsuwa, who calls out to her Saiji and the rest of their comrades. They respond and redo their formation again with Itsuwa being the focal point. With the tube spear to reduce the friction between the spear and palm, Ituswa strikes Acqua of the Back with her spear. It turns into lightning in the shape of a cross, the execution method that was used on Son of God, therefore the weakness of the Saints that has their bodies having the same properties as that of the Son of God, strikes down on Acqua of the Back. It was the Saint Destroyer, the culmination of the Amakusa Christians efforts to truly know their Priestess, Kanzaki Kaori, a Saint herself, in order for them truly be by their side.

But not a scratch came upon Acqua of the Back, for he had grabbed Itsuwa's spear before it hit and modified and weakening it. Slightly impressed, Acqua of the Back tells them that if he was a mere Saint then it would most likely finish him off, if not for the fact that he is also a member of God's Right Seat. He then blows her down to the 4th level, ripping the screen up. As she falls, Itsuwa and the others use barrier spells for her descent, but this was not enough, and Itsuwa falls to the floor below. Bored of the battle, Acqua descends down to her and asks Itsuwa if she is willing to hand Touma's right hand over to him or choose being killed. But Itsuwa answers with her actions, standing up once again to challenge him. Seeing this, Acqua of the Back summons the water from the 4th level and forms it into a hammer. He tries to strike it down upon Itsuwa, but ceases before doing so. Acqua of the Back notices something and disperses the spell. He tells her that she should her master and leaves, for Kanzaki Kaori has arrived to challenge him. The Amakusa Christians watch from the distance as Acqua of the Back continues to dominate Kaori and the battle falling down into the 5th level of School District 22. Right now, they are powerless, and the injuries and battering they've incurred from Acqua of the Back playing with them have left some of them to lose their grip on their weapons. Moreover, because Kaori is protecting them, it seems that their efforts have come to not, for once again their Priestess stand in front of them to protect and not them standing besides her to aid her. The Amakusa sink into despair as the battle between the Saints continue.

Kaori is at her limit, and is slowly falling back, and her strength wavering. As Kaori looks on, Acqua of the Back continues to look down on her and the Amakusa Christians. There is just too much of a difference between her and the pure talent and genius of Acqua of the Back. He points out that he will crush them for they chose to fight him regardless if they are incapable of fighting back, to which Acqua of the Back just looks down upon them. Kaori steps inside the shoes of Acqua of the Back and discovers that they are not that different. She is a Saint, and though she cared for her comrades, she looked down upon them, never letting stand beside her in the battlefield, trying to control everyone so that they would not get hurt. With that Kaori realizes her own foolishness and her own weaknesse. Here, she discovers that she still had the power to challenge Acqua all along.

Upon the 4th level the Amakusa Christians heard her call from below; Kaori calls out to her comrades to lend her their power. And their bodies trembled in their place, and those who have lost their weapons in their frailty pick them up once more, for their leader has come 'a calling. They were now recognized by their Priestess, they are no longer a burdern to her. Now gathered, Saiji gives his last instructions as the Subsitute Supreme Pontiff, their Priestess, to where the Amakusa should go. They gather around their Priestess with a jubilant shout, surprising Acqua of the Back. He tells her if he is willing to have the weak help her to save her own life. However, Kaori reveals that she was the weak one, for not believing in her Church's abilities and strengths. Because of these insecurities in wanting to protect what she deemed weak she mad mistakes allowed holes in their formations and putting her comrades in danger. And that is why she called her Church back to her, for she can trust herself to them, to utilise their ability to the maximum. Acqua of the Back however, is unperturbed, and Kaori meets her rod with her sword, however, this time the Amakusa Christians cast defensive spells to reduce its impact. As their battle goes on, Kaori points out that Acqua of the Back's strengths are also his weakness. The reason why he can indiscriminately use his Saint powers without his body overloading is because of his Divine Mother's Worship. However, this make his weakness be the Saint Destroyer, as proven by the fact that that was the only time he used a magical defense. Kaori says that to regular Saints, it will only cause them to be unable to move for several seconds, but for someone like Acqua of the Back who has the attributes of the Son of God and the Divine Mother, he will surely self-destruct. The Saint Destroyer forcefully destabilizes the balance that Divine Mother's Worship gives that allows Acqua of the Back to use his Saint powers beyond normal Saints, that is how he can be beaten. Acqua of the Back smiles at this revelation, continuing his assault on Kaori. She strikes at the buildings with her wires around Acqua of the Back, and there he discovers that she has formed from the rubble, a crown of thorns, an iron picket, and a large cross, the method of execution of the Son of God, the weakness that all Saints inherit. Acqua of the Back begins to waver, for surely, though to an ordinary Saint, this method won't do much effect, to someone like Acqua of the Back it spells out his execution. Itsuwa comes close again with her spear, symbolizing the Spear of Longinus that pierced the Son of God. However, Acqua of the Back isn't numbered yet. Impressed by their feat, he jumps again and uses the artificial moon of School District 22 to symbolize the attribute he is aligned to. He falls back the earth with his rod aiming at them, exuding a tremendous magical power. In danger, Kaori prepares to defend against Acqua of the Back, collecting all the symbols throughout history, forming this spell at the last second, turning Kanzaki Kaori into a shield.

Acqua of the Back strikes down, but to everyone surprise, the place where they're standing remains intact. Acqua of the Back's spell was destroyed by the arrival of Kamijou Touma, holding unto the rod that was fused with magic a moment ago. Touma falls down and seals Acqua of the Back. In his shock, Acqua of the Back could not see Kanzaki Kaori charging towards him, holding his rod and shoulder. With his movements sealed by Kaori, and magic negated by Touma as she tries to shake her off. Itsuwa charges towards with her spear. Acqua of the Back accepts the fate and determines to face it to the end. There, the spear strikes him, piercing his abdomen to the back. Crosses of light appear behind Acqua of the Back, intersecting in the middle, causing Acqua of the Back to fly back due to the impact. They later witness Acqua of the Back being propelled into the artificial lake of the 5th level, and then self-destructing, utterly destroying and boiling the lake into a pillar of steam.

Itsuwa is by Touma's side after the battle. Touma awake to find her. She tells Touma that it is only normal for him to be unnable to move after all he had went through. Here, Itsuwa says that they Aqua of the Back is still alive and retreated, as well as being no one dead in the Amakusa or even among civilians. Touma then shows his nonchalance regarding the matter, saying that it was amazing that they've managed to beat him, a member of God's Right Seat and a Saint. Itsuwa is surprised by this from someone who contributed the most, despite her being the key to his defeat using the Saint Destroyer, as they have not only beaten him but did not have a single casuality. Touma tries to get out of bed again, needing to go to school, but Itsuwa stops him pushing down and making her face close to his, making her blush. Suddenly, Index come around, angry at him for having Itsuwa sit beside him instead of her as well as not yet apologizing for leaving the hospital on his own. Itsuwa joins the fray, asking why he ran over to where Acqua of the Back despite his condition. Hearing Acqua of the Back's name, Index becomes even angrier at Touma for facing such a powerful foe without consulting her for help. Needless to say, Touma is disraught over their double team.

British Royal Family Arc
Itsuwa is browsing magazines in the Japanese District of London, trying to find ways to make Touma fall for her after hearing about how Kaori has made her move with the 'Ero-Fallen-Angel' cosplay. She despairs that because of how salient Kaori's move is, it's likely Touma has completely fallen for Kaori to the point that he might have even forgotten that Acqua has attacked him. She sees the 'Greater Spirit/Fairy' cosplay, and thinks about getting it in order to combat Kaori's attempt. She eventually decides not to go through with it while rumpling up her hair in embarassment at the thought. Itsuwa believes it would be too embarrassing - and thinks this might be the difference between a normal person and a saint- a saint strikes decisively rather than having to think about it. In her deep thought she fails to hear the rest of the Amakusa's hiding in the attic and spying on her from a corner of the ceiling, talking about buying the cosplay first and giving it to Itsuwa - Tatemiya has somehow already got Itsuwa's three sizes and they plan to order the cosplay after all. This is all done so that they can witness a 'battle' between Kaori in 'Ero-Fallen-Angel' cosplay and Itsuwa in the 'Greater Spirit' cosplay.

Later, Itsuwa goes to pick up Touma and Index from the airport, only to find that Sphynx is the only one that has made the journey on the supersonic plane. She ends up drowning her sorrows at not being able to meet Touma at one of the houses in the Japanese District. Later still, other women from Amakusa tell itsuwa that the "youth with black spiky hair" has arrived, much to Itsuwa's horror as she is still half drunk and has bad breath. The youth in question walks in just as Itsuwa is preparing, but it turns out to be a practical joke played by Tatemiya, and Itsuwa in her fury throws a small table at him - knocking him off his feet.

When New Light infiltrates London, she and the Amakusa Christians later intercept Bayloupe of New Light near the entrance of a subway station. Bayloupe is surprised, to which Itsuwa says that the Amakusa Christians are proficient in blending in with the environment, which allows them to detect people who do not belong. Itsuwa tells her that she will be taken to the Tower of London, but she refuses, there she puts on her special horns and prepares to leave with her case that supposedly contains a spiritual item. Itsuwa responds and strikes as Bayloupe, however, she meets it with her own polearm. As they clash, the other Amakusa Christians take out their hidden weapons, seeing this, Bayloupe smashed the wall she was leaning on previously, intending to flee. Itsuwa tells Saiji and the others to guard the entrances and exits, and proceeds to fire a gun with blanks in the underground area, forcing the people to quickly leave as Itsuwa makes her pursuit.

Itsuwa runs towards Bayloupe and sees that she running directly into the tunnel instead of getting on a train, after their gaze clash, the battles start anew. Bayloupe moved first, still holding her case, she swung her spear-like weapon to throw the sign it held. But Itsuwa however easily cuts it down with her seven wires. Itsuwa assumes that what Bayloupe is holding is not a spear and belongs to the thunder god Thor. Bayloupe tells her that she is hoping she won't say it is Mjölnir as it would be just stupid. She indicates that Thor in legend used other weapons and tells her that her steel glove, her polearm, is based on that story when Thor borrowed from a female giant, a weapon for a girl to use. Bayloupe explains that not only is Thor a thunder god but that of god of agriculture, and that they decided to prepare a weapon that isn’t just used as a means of attack and possesses the softer side of a god of agriculture. Bayloupe tells Itsuwa the legend of Thor borrowing a belt, an iron club, and iron gloves, and tells that it be better to have all those in one spiritual item. At that moment, her four bladed steel glove sunk into the tile floor, and swung debris towards Itsuwa. She defends herself, and tries to attack but she is caught unexpectedly by Bayloupe's use of her steel gloves to throw the powder explosively upon her and she is cast aside. Bayloupe jumps up and gathers dust again, Itsuwa at first wanted to block it but decided to jump to the side. Itsuwa flew spinning through the air and hit with debris as a result of the Bayloupe's attack but was spared froma direct attack. Bayloupe renews to attacka gain, while Itsuwa lost her balance. With a direct attack receive by Itsuwa, she is thrown to the ground and knocked afar, destroying the handle of her spear. Boasting her on success, Bayloupe states that she'll be using Gjallarhorn next. She explains that with the horn, she can temporarily use the thunder attribute, though differently than that of Thor using Mjölnir. She warns Itsuwa to remain where she is unless she wants to be turned to ash, and seemingly complies with Bayloupe's threat. Bayloupe then boasts of how they will bring about change into the United Kingdom, and begins riding on her polearm, the steel glove. With it, she jumped from platform to platform at high speed into the train tunnel with the case. After she was gone, Itsuwa reached over to a microphone on a pillar used for announcements. There, she announces to the now-troubled Bayloupe that she is trapped in the Necessarius Underground Labyrinth. She tells Bayloupe to make sure she works hard on not dying as someone failed in regulating the difficulty in the labyrinth that Bayloupe is now, saying that it is off limits now because people kept dying in it.

Sherry meets up with Itsuwa in the lost article storage room after the latter successfully traps Bayloupe in one of the labyrinthine halls of Necessarius that is used for training. Here, Sherry notes that the facility has been toned down a bit since its use. Itsuwa apologizes to Sherry for calling her at such a late hour, to which she states that she doesn't mind as she is not a nun who follows some ridiculous rule. Sherry is bothered that she might have to help the Knights of England, but pays no heed to it, and asks Itsuwa the reason she called her. She analyzes the case that Itsuwa took from Bayloupe, and discovers that it can apparently change shape and is of Norse origin. Itsuwa accidentally taps on the beaten up case, which opens itself up, and at that point, it transforms into a large 10 meter long canoe. After commenting and comparing Itsuwa's clumsiness to Orsola, Sherry concludes that the case is a magical item that mimics the legendary Skíðblaðnir of Norse mythology. Sherry states that it is not the case or boat that is important, but the thing that it carried. Itsuwa says that in her battle with Bayloupe, she determined that it was not a dummy since she was protecting and carrying it fiercely and carefully. Sherry states that it may not be a dummy, and tells Itsuwa that she might investigate but suggests that she should go talk to Agnese first who is investigating New Light's base in Edinburgh. With that, she bids Itsuwa farewell, and says that she should head back aboveground and get rid of the rest of New Light.

Itsuwa contacts Agnese as she makes her for the exit telling her of the new discovery. Agnese apologizes to Itsuwa for not getting any information on Skíðblaðnir, but states that they will now proceed to search information regarding New Light's plans through what Itsuwa discovered, and asks to confirm if they had only taken out 1 of the four members of New Light. Itsuwa tells Agnese not to worry as Kanzaki Kaori had just beaten another member. Itsuwa later regroups with Kaori and the other Amakusa Christians after severing her connection with Agnese.

English Civil War
As the British Halloween begins and Princess Carissa shows her true colors, the Amakusa Christians hijack the seaplane moored on the lake on Hyde Park after evacuating the Necessarius Women's Dormitory, as the Knights of England under Carissa, has shutdown all air transportation. The plane is later spotted by Carissa and Knight Leader, and later has Kanzaki Kaori drop upon them to confront them directly and the coup. The Amakusa Christians later arrive at Folkestone and sent scouts to search for Touma, Floris, and Princess Villian. Moreover, they also retrieve their Priestess Kaori after her defeat at the hands of Knight Leader, and began to prepare for a defensive battle. One of the Amakusa Christians suggest breaking formation in order to aid Touma in searching for Index, but he declines and states that the best move is to have Kaori back in shape and protect Villian with all their combatants. Despite their insistence, the Amakusa Christians reluctantly accept, though Itsuwa was blushing and tried to force herself to go with Touma, the others held her back.

After the now normal Saint Acqua of the Back saved Kamijou Touma and Index from Carissa, Touma and Index later meets up with the Amakusa in the forest of Folkestone. The Amakusa Christians have heard of the explosion caused by Carissa in the battle earlier and had come to investigate without being detected. They later go into the seaplane they used, crammed with the other members of the Amakusa Church. Tatemiya Saiji reports to Touma that Carissa is heading for Buckingham Palace, while the other Amakusa Christians keep egging Itsuwa on. Continuing with his report, Saiji states that to stop the coup, they have to stop Carissa, and states that unlike their Priestess, who was born with her power, Carissa only has the Curtana Original, which if they can destroy, would rob her of her power. Touma later sees Kaori, whom upon seeing his gaze, reports that the Agnese Forces and Sherry Cromwell are currently in battle, and states that she is still recovering before she can go back to fighting form. Touma then asks if she is all right, to which she says that she wishes that she can tell that it wasn't a problem. She smiles, and looks at Saiji who simply nods. Saiji then speaks about Acqua of the Back's involvement, and states that it may be in their favor. Touma, however, doubts his allegiance and says that he doesn't even know if truly did defeat the Knight Leader. Saiji replies that he has scouts that determined that Acqua of the Back had fought the Knight Leader, and since the former is moving about, it can be assumed for now that the Knight Leader has been defeated. This means that the only one standing in the way is the troublesome Carissa.

Kaori then asks what happened to Queen Elizard and Archbishop Laura Stuart, to which Saiji states that he hasn't receive reports regarding them, and that, according to the Knight's communications network, the two of them at least attempted to escape while being transported from Windsor Castle to London, at which point they have no idea what had happened afterwards. Touma asks if Elizard has something up her sleeve that can end the crisis in one shot. Saiji replies that they can hope for her having a kind of direct battle ability, but even if she does not have a plan, her mere existence is very valuable both in domestic affairs and in diplomatic affairs, as such, the real way to defeat Carissa's new order in the end may lie in her. Saiji then restates the importance of preventing Carissa from using the Curtana Original. Touma doubts that they can enter the now occupied London and get to Buckingham Palace, but Saiji states that they can at least sneak into it. Saiji states that there is the Victoria subway line that runs directly beneath Buckingham Palace. Saiji quizzes Touma on why Carissa would go back to Buckingham Palace. After giving the usual responses, Saiji explains that the reason is because of Curtana Original, which has too much power, as such Carissa needs a large facility to suppress its power if it goes out of control. The facility in question, is built within the Palace where the Curtana Second is supposed to stay for the majority of the year. Curtana Original was lost in history after going out control, as such it is likely they have planned on a way of preventing Curtana Original from going out of control. Kaori later adds that they have a theory that the large facility in Buckingham supresses Curtana Original's power by reversing the flow of the magic power. Since Carissa has entered Buckingham Palace to supress its power, Kaori states that now they have a real chance of making it go out of control, rendering it unusable.

Continuing with Kaori, she states that the knight's connection with Carissa is not as strong, as they are being led by her instead of their leader. Kaori says that the knights joined in with the coup d'etat with her as they deemed that it was the most beneficial path for England. Moreover, they will turn their backs on her the moment they determine that continuing to follow her would be disadvantageous for England. This implies that whether or not she can use Curtana Original is directly linked to the success or failure of the coup d'etat. Touma then questions on how Buckingham Palace having the supressor to Curtana Original if they said that it didn't have magical devices, to which Kaori says that there are no magical devices in Buckingham Palace during times of peace, but a subway line runs beneath the palace. A special railroad car with a magic circle on it is kept in an area branching off from the normal track. The special car is set up so it can be promptly taken to the area directly below Buckingham Palace when Curtana Original is headed out of control. Kaori states that the Anglican Church's plan is via using the air fortress Coven Compass to use a large amount of magic power to forcibly interfere with Curtana Original via the subway in an attempt to send it out of control. Kaori states that Coven Compass is 500 kilometers away from Buckingham Palace, as such, Church members are setting up relay points to guide the magic power. Touma concludes that they are heading to London to confront Carissa after Curtana Original has been sealed, but Kaori is hesitant to say. Saiji then tells Touma that because the special railroad car used to bring Curtana back under control is kept in an area branching off from the normal track, the part where it branches is protected by a magic barrier. This necessitates with them needing to destroy the barrier, to which Touma concludes that they will need to go into a subway station near Buckingham Palace and destroy the barrier with his right hand. However, Saiji states that there is a security measure put up on London which allows the Knights of England to detect them in a map. In conclusion, people who can refine their own magic power cannot take part in the plan. Moreover, without a member of the royal family like Princess Villian, they cannot interfere with the magical barrier within the subway tunnel or the special railway car with the magic circle. In the end, the mission to enter the subway lies at the hands of Touma, Index, and Villian.

Itsuwa is later the first one to contact Touma and company after their covert mission under Buckingham Palace, referencing that she is now free from smelling of alcohol. Itsuwa warns them that the plan to attack Curtana Original is already on its way and that the special railway car is heading for them at tremendous speed, telling them to get out of the way. Itsuwa then says that they are going to link the center of Coven Compass with Curtana Original via the special railway car. The reversing of the flow of power will create a large scale release of magic power. Because of this, the knights will detect the abnormality and head there to investigate, moreover, she says that there is also a major risk of getting caught up in the ensuing explosion, forcing her to reiterate that they should head back.

After the successful mission of Touma and company, Saiji watches the magical explosion of Curtana Original going out of control in Buckingham Palace with a pair of binoculars. It was a calm before the storm, and the members of the Anglican Church, including the Amakusa Christians and the Agnese Forces, have gathered in the verdant outskirts of London. Saiji mentions that they succeeded in weakning Curtana Original but they were still affected by its reaction. Ushibuka then states that it is because of the telesma emitted in all directions with the second princess at the center, affecting the spiritual items and facilities within London, and destroying three small churches in the process. Kouyagi adds that the Telesma in London is incredibly dense, so much so that using magic within London would envelop the city in an explosion. Saiji agrees, stating that they could mentally take down the knights now that Carissa has been weakened further. Isahaya comments that they need to wait for the Telesma in London to diffuse before they could attack, though he worries that the Curtana Original might be restored and the Knights of England would focus on defending Buckingham Palace in the meantime. Saiji states that though he is unsure of the knights, the Curtana Original is too strong and cannot be restored easilty without leading into catastrophe if it fails. With that, Saiji concludes that they have a little break, though states that it is also a preparatory period before the final battle. Tsushima retorts that they should do their jobs properly then, to which Saiji and other males of the Amakusa begin arguing back against her. However, Tsushima is unperturbed as she sees them looking at Itsuwa and her apron using the binoculars.

During the calm before the storm, the Amakusa and the rest eat to restore the stamina they lost from the fleeing and battling. While Itsuwa is flustered on what she should do with getting close to Touma, Saiji appears having apparently gotten the Great Spirit Revealing Maid outfit. Saiji reveals that the designer was from London, as such he picked one up just after the coup d'etat started, to which Itsuwa just freaks out. Seeing this Kaori, lets out a sigh of relief, believing that her own maid outfit was lost back in the ensuing chaos of evacuating the Necessarius Women's Dormitory. But Saiji reveals that he also picked up both the Fallen Angel Maid and the Fallen Angel Ero Maid from the dormitory, much to Kaori's befuddlement. The Amakusa men then started talking about Kaori having other more erotic maid outfits, infuriating her even more. This was apparently because they have never seen their Priestess in a Fallen Angel Ero Maid outfit. All the discussion about maid outfits reached the ears of the Agnese Forces and even Sherry Cromwell and Orsola Aquinas.

They arrive at London, groups splitting up between 20 trucks heading for Buckingham Palace. The Amakusa Christians have prepared spells against the checkpoints, but have discovered that the city has none of it, to which Kaori assumes that the knights' forces are concentrated in Buckingham Palace. Kaori plans to use Touma as a powerful but slow moving mobile cannon, where she and the Amakusa Christians will bait Carissa towards Touma's direction in order for him to destroy Curtana Original. The operation starts with Coven Compass and Selkie Aquarium's long ranged magical bombardment of Buckingham Palace, which would allow them to get close to the Palace as Carissa will be too busy defending against them. Complicating matters even more, Carissa summons her own fleet of mobile fortresses, Griffin Sky. As Kanzaki Kaori arrives to do battle with Carissa after saving Touma and Princess Villian, the Amakusa Christians, the Agnese Forces, and other members of the Anglican Church arrive, such as Orsola Aquinas and Sherry Cromwell with her Golem. All of them arrive in shock at the level of battle Carissa and Kaori were fighting on, however, they later realize where they were in and try to either assist Kaori or attack Carissa. However, despite the number advantage, they are unable to take down Carissa. The Griffin Sky mobile fortresses however arrive as her reinforcements, and rain lances upon Sherry's golem, raining debris threatening to crush the rest of the forces, while Agnese and Lucia frantically try to take cover. Seeing how the Griffin Sky could thin their numbers, Kaori orders the Amakusa Christians to split into teams to deal with Carissa and the Griffin Sky mobile fortress. The Amakusa Christians quickly do as their told, and though one of which was not taken down, Kaori was able to use it to her advantage. Swinging the lance it had to hit the other Griffin Sky mobile fortresses and attack Carissa. Itsuwa later encourages to make teams in order to increase their attacks on the Griffin Skies, to which the Amakusa Christians do so quickly.

Saiji and Itsuwa, close quarters fighters, are struck down by a projectile attack by Carissa. After Villian catches Carissa off her guard by showing off some unexpected magic through the use of her bowgun and the magic power Cover Compass was bombarding, Carissa tries to strike down Villian. However, before she is able to, Saiji, Itsuwa, and the other Amakusa Christians take her away to face Carissa themselves. They were faster than before thanks to Villian's spell that Carissa thought was meant against her. Carissa tries to desperately to remove the cores falling down to suppor the close quarters fighters, however, when she has a swing, her Curtana Original doesn't cut a dimension as it is negated by Touma before she is able to do so. Villian once again fires her bowgun, and Carissa tries to defend herself, however, it was all but a ruse to allow Index to alter the trajectory of the Coven Compass' attack spell towards her, hitting her.

However, Carissa is not felled by the attack due to the Curtana Original, though there are a few scratches on her body. With Griffin Skies wiped out, Carissa calls for a bunker cluster missile to be fire on Buckingham Palace. Running out of time, Kaori sets up a defense barrier in the air with a range of 3 kilometers in every direction to intercept them. However, as Kaori was busy she is totally defenseless, Carissa strikes her but she manages to evade. However, the construction of the defensive spell was interrupted and Kaori starts over again, but she did not make it in time. Explosions then rang out, but despite this, the defensive spell was successful in defending London, and only a few managed to hit through the gaps of her spell. Touma later calls out to Saiji among other after the bombs fell but there were no respones. After Princess Riméa's broadcast revealing Carissa's intention in the coup d'etat, the Knights of England later appear in the battlefield, some of them heal the members of the Anglican Church. It can be assumed that some of the members of the Amakusa participated in attacking Carissa with their spells during her clash with Kaori, Acqua of the Back, and Knight Leader. Moreover, they may have also been empowered by Curtana Original after Queen Elizard used Union Jack to distribute its power to all the citizen's in the United Kingdom, and later aid against Carissa. They may have also witnessed Touma destroying the Curtana Original and defeating Carissa.

Kaori and the rest of the Amakusa Christians later treat the wounded after the end of the coup d'etat. Saiji states that since Touma got the best part in ending the crisis, Kaori once again owes Touma again. Kaori tries to persuade them that she has no debts as everyone joined forces and the achievements should be divided equally. But the Amakusa Christians do not listen and instead, argues about which maid outfit Kaori should wear. They may also have gathered around Index after Fiamma of the Right took away the external controller for her John's Pen Mode, as well as Touma declaring to hunt down Fiamma of the Right.

World War III
Along with their Priestess, the Amakusa Christians participate in the Battle of Dover Strait, anticipating the French crossing its waters. Agnese Sanctis notes on how the world has changed, and later notes that it is 100% perfectly accurate to say that French forces are going to invade England through Dover Strait, which was confirmed immediately afterwards, as 1,000 French magicians walk on the sea's surface by solidifying it. With the initial assumption that there would be a naval battle, their ships and their tactics are now rendered useless, Kaori and the Amakusa begin their battle agaisnt the French, and are later joined by Princess Carissa.

When Lessar tries to seduce Touma hundreds of miles away from the Battle of Dover Strait, Itsuwa feels a chill along her spine, to which Saiji asks what's going on, though she states to him to pay it no mind. They later witness the arrival of the Mobile Fortress Glastonbury and the ensuing clash between Carissa and the Maiden of Versailles.

The Amakusa Christians most likely later joined Kaori and the Agnese Forces to go to the Eurasian continent, towards the Russian battlefield where both Academy City and Russian soldiers have collapsed. They later witness another Golden Arm pop-up nearby, which is later cleanly cut down by Kanzaki Kaori, shocking the soldiers present.

Homecoming Arc
Itsuwa is the one who delivers the shocking news that Touma is alive after the advent of the War to Kanzaki Kaori before her mission to intercept the Radiosonde Castle, much to her surprise.

In St. George's Cathedral, as Itsuwa becomes frantic due to the information that Touma is still alive and in Academy City, Saiji offers her a bamboo sword to spar in order to clear her thoughts. Angelene, seeing this, calls out to Lucia regarding a "samurai battle" that is taking place, but is scolded by Lucia for cheering on a fight, unbefitting of a nun. Angelene becomes excited however, and references Shinken Shirahadori, trying to imitate the blade catching technique. Seeing Angelene's excited demeanor however, makes Saiji nervous, as it would seem that not pulling it off would make Angelene disappointed. Saiji tells Itsuwa that they have no choice, and tosses his bamboo sword aside, in order to try out the sword catching technique, which surprises Itsuwa enought to raise her voice, and gather more nuns towards them as well as the other members of the Amakusa. Itsuwa attacks Saiji, and he is unable to catch the sword, hitting him on the head. Because of this however, Itsuwa sees the need to follow through, for the sake of Saiji as it would be embarassing. She tells Saiji that it was just a practice run, as such, it doesn't count. They try again, and Saiji is hit in the head again, much to both their frustration. Kouyagi then comes up and offers them an imitation sword steel-forged sword, after Saiji tells her that the bamboo sword throws her off her timing. Saiji is expectedly horrified with it, and is then hit in the head again by Itsuwa, but this time, with the iron-forged sword.

As Saiji writhes in pain, Itsuwa still complains that her timing is off, and that a real sword is needed for Saiji to catch it. Just then, Tsushima offers a real sword, a Bateren-dedicated Kanemitsu Toushou. Saiji is utterly terrified, as Itsuwa takes the sword and her face is shadowed as she prepares to finish their demonstration with Saiji. Angelene's eyes sparkle at the prospect of finally seeing the sword catching technique, but Saiji wants to back off. However, Itsuwa doesn't want to Saiji to gain more shame. Seeing that Itsuwa will not yield, Saiji steels himself, and hopes he'd gain some hidden ability like on those protagonists.

Sidestories
After the events of the Orsola Aquinas Rescue Arc, Itsuwa and the rest of the Amakusa Church partake in the Necessarius Special Admission Test within the Necessarius Underground Labyrinth, minded by Freadia Strikers. As the test continue, they discover that Fredia's communications have been intercepted and that they are talking to a fake one. Moreover, people pretending to be the Amakusa Christians have also passed the test, and have now the ability to bypass the magic locks of Necessarius facilities, and Necessarius none the wiser. With this, the Amakusa Christians are framed and are now targeted by Necessarius, forcing them to clear their name.

Toaru Majutsu no Index (PSP game)
Itsuwa appears as one of the first playable characters in the game roster. With her spear, she can attack from a considerable distance and can switch between the four elements with it for a variety of effects. Her Overdrive is the Seven Blades of the Seven Teachings, and her finishing move is the Saint Destroyer.

She appears in Kanzak Kaori's story as her partner, where they are tasked to find and stop a magician who has infiltrated into Academy City. After several incidents (such as being accused of being a large breasted terrorist by an army of middle schooler girls who have the same face) Kanzaki finally runs into her target, Acqua of the Back.

Itsuwa appears with her partner with Index in Mugino Shizuri's story after she defeats Kamijou Touma and Tsuchimikado Motoharu angry for what she has done to him. Finally, in Mikoto's story, she is one of the females caught up in the insanity of Mikoto chasing after Touma due to him taking the Gekota Chocolate before her.

Amakusa-style abilities
As being part of Amakusa, all of what Itsuwa wears is part of his magic and is deliberate. The Amakusa Christian’s specialty is secrecy, since they’re Christians whose nature is to deceive others; they hide the teachings of Christianity inside Shintoism and Buddhism completely, and use rituals and techniques as part of their greetings, diet, and behavior in their everyday lives. They cover all their tracks so that others won’t even notice their existence. These teachings have been passed down from generation to generation.

Friuli Spear
Like all the Amakusa Christians, Itsuwa carries a weapon. Itsuwa wields a Friuli Spear or Friulian Spear (海軍用船上槍 (フリウリスピア) ) that is apparently used in navies. The spear is most likely a reference to the coat of arms of the capital of the Friuli-Venezia Giulia region of northern Italy, Trieste, which bears a spear or properly referred to as the corseque. The spear is 70 centimeters long. The spear's grip is split into 5 parts that came together into a single rod when connected using their sockets that looked like gas valves. When she needs to use it, she can connect the attachments making a single spear, allowing for concealment and ease of carry at the cost of the spear's strength. The pieces are replaceable after they are broken allowing for Itsuwa to remake the spear even when it has been broken.

She is able to wield it expertly, able to take down several enemies with a single swing, and relieve a cornered position with it, as what she had done for Lucia during the Battle of the Adriatic Sea. However, she is most effective in team situations, unlike the human wave tactics that the vast Agnese Forces use, the Amakusa Christians, with its at least 52 combat-ready members,, have been shown to be much more focused on teamwork and unity. Indeed, during their protracted battle against Acqua of the Back, Itsuwa with her spear was the focal point of their strategy.

Known spells
Despite her magic being the same as that of her Amakusa comrades due to their shared history, Itsuwa has show spells that are either unique to her or is most well-known because of her usage.

Saint Destroyer
The Saint Destroyer (聖人崩し) requires the Amakusa Christians to set-up a formation, with the attacker at the center, the Saint Destroyer is a magic attack that works on Saints alone. On a normal Saint it will only cause them to be unable to move for several seconds, but for someone like Acqua of the Back who who has the attributes of the Son of God and the Divine Mother, he will surely self-destruct. Itsuwa alone is shown to be the only who is capable of casting this spell. It is because her wielding a spear, it is a reference to the spear that stabbed the Son of God, the Spear of Longinus as explained by Idol Theory, a weakness of the Saints. The attack requires for her to use a tube using a towel with her spear in order to reduce the friction between her palm and spear when pierces the opponent with it.

It appears as blueish-white purple electricity, causing an explosion, and the electricity forms into a Cross, the weakness of Saints through Idol Theory, as Saints have a body that is similar to the Son of God who was crucified on a cross and was pierced. Explosions continue to occur after the magic attack is dealt. Other additions can be appended to increase the strength of the spell, specifically they should be related to the Son of God's crucifixion, such as a crown of thorns, a picket, and a large cross.

It was created by the Amakusa Christians after the departure of Kanzaki Kaori in order to understand the burden of being a Saint, and in theory, surpass whatever she feels as a threat.

Other spells

 * Ley line damaging spell: Using found objects that serve symbolic properties according to Idol Theory, Itsuwa can use an Amakusa-style ley line damaging spell using her spear. After arranging the objects into a circle it will glow, and Itsuwa merely needs to strike her spear deep into the circle and turn it like a key until the ley line is disturbed to her needs. Severing a ley line completely, however, requires a lot of people.
 * Seven Blades of the Seven Teachings (七教七刃) is a technique used by Itsuwa using steel wires. It is similar to Kaori's Nanasen, as it uses 7 steel wires that acts as superfine blades to attack a target at once at 7 different directions. It is unknown if it is just Nanasen using a different name, or derived from it. Itsuwa uses her spear instead of a sword to use the technique.
 * Healing Magic: A notable example of this is Itsuwa using found objects to create a healing spell after Acqua of the Back's brutal beatdown on Touma. Itsuwa fails to heal Touma after his right hand negates the spell.
 * Damage transference charm: Which transfers part the damage she takes, into her clothes. She also has a spell that uses her clothing as a scapegoat.
 * Icy Night Wind (冷たい夜気): Magic that is casted on the tip of Itsuwa's spear, creating an explosion that can tear apart asphalt.
 * Reproductivity that Plants Possess (植物の持つ繁殖力) or Scattered Grass (雑草) improved her spear's durability by adding about 1,500 layers of reinforcement through resin, which symbolizes the age of trees. It uses an image of the growth of plants and amplifies hardness of her spear according to the passage of time.
 * Life force concentration spell: Itsuwa knows of one method that allows her to concentrate the life force needed to refine magic power and concentrate it on a single point. It was a standard method of creating a boost. Itsuwa uses the spell to sever the connection, that flow of power, of a cursed wax doll that had taken her blood to read her life force, and in turn make attacks that she cannot avoid. The spell can only be used by women and is based on the legend of Adam and Eve. The chant: "This is the story of paradise before it was corrupted by sin." "God created man and arranged to give everything to him, but the perfectness left the man feeling uneasy. The man could not live in solitude and the animals living in paradise were not enough to fill his heart." "God, being generous, was willing to use his power to fill the man’s heart, but the man did not choose that method." "That one man should have been enough of a beginning in paradise. Two starting points are not needed. Each subsequent man created from then one should have been a single point." "God pitied the lonely man and created a partner from his rib. That partner’s name was Eve. That is the name of the starting point and model for all women!" "All women come from the missing rib and must join with their lifelong partner through marriage!!"
 * St. Andrew's lightning spell: A spell which increases the accuracy of Itsuwa's spear. To use it, Itsuwa carves an 'X', the symbol of St. Andrew, a patron saint closely related to lightning, on the spear's handle. She then throws the spear, which absorbs any lightning that strikes it and becomes a mass of bluish-white light which strikes the target.

Other abilities
Itsuwa has an international license and she can pilot cars, motorcycles, mini-boats and (with difficulty) a helicopter.

Kamijou Touma
Itsuwa has been in love with Touma ever since the La Regina del Mare Adriatico Arc. She relies on the advice of Tatemiya and the other Amakusa's to get close to him. A common tactic of hers is to offer him a wet towel. She also gets excited by just a bit of physical contact with him, such as holding hands with him or getting hugged while riding a motorcycle together. Although initially embarrassed by the idea she is eventually very excited by the idea of wearing an Great Elemental Fairy costume (pictured below) for him. It has been stated that Itsuwa is prepared to die for Touma.

Kanzaki Kaori
Kanzaki is Itsuwa's superior in the Amakusa Church, and like all of the other Amakusa's she looks up to her a lot. Itsuwa considers Kanzaki better than her at everything, including looks. Despite this respect she has stated that she will not hand Touma over to her or anyone else despite being aware of Kanzaki's feelings for him.

Tatemiya Saiji
Tatemiya is also Itsuwa's superior in the Amakusa Church. Itsuwa relies on him for relationship advice with Touma.

Design evolution
Details in Itsuwa's design has changed as her prominence becomes more apparent in the later half of the Toaru Majutsu no Index series, though her overall design remains the same. According to Haimura, due to the theme of Amakusa wearing clothes that would not make them stand out, Itsuwa was drawn to wear features that would never be seen in reality, though are much more common in moe characters.

By volume 14, and in Itsuwa's new clothes for that volume, Haimura had the idea that the Amakusa's would try to keep up with the latest fashion to better help them blend in. For the volume 16 clothes change Ituswa has, Haimura states that since she is a moe-type character, her design must follow a "cute" style, and must not be altered too much.

Quotes

 * (From volume 16): "It won’t do if I don’t do my best."
 * (Thinking about Touma, from volume 16): "That guy managed to fight back the two "God’s Right Seat" members, Vento of the Front and Terra of the Left, but I’m certain that I can do something, so I've got to do my best"
 * (To Touma regarding Kaori's clothes, ibid): "You, you suddenly gave a shocking comment about the Priestess!? That isn't because it's obscene, but rahter the spell composition that requires asymmetry!! It was deliberately made like that to allow the balance on both sides be used even more effectively, and not meant to deliberately show off the curves on her body or whatsoever—!!"
 * (To Acqua of the Back, ibid): "…Even if it’s me…I have my own determination."
 * (To Acqua of the Back, ibid): "…If you have something to say, say it later. After I beat you to a pulp over and over again!! If your jaw isn't all broke, I'll let you talk all you want!!"
 * (Thinking about Kanzaki, from volume 17): "E-Erotic Fallen Angel Costume…!! To prepare such a horrifying secret weapon, as expected of someone as formidable as the Priestess! To wear such a thing, wouldn’t all the memories of that battle against Acqua of the Back be gathered at one point…?"
 * (To Bayloupe, ibid): "We are from Necessarius, the 0th Parish of the Anglican Church. Do you understand?"
 * (To Saiji, frome volume 18): "Wh-why are you suddenly jumping in here and talking about a roadshow? I don’t understa-hic!?"

Trivia

 * Fans have speculated that Uragami, the Amakusa Christian girl that Touma fought and saved from a fall in volume 7, may actually be Itsuwa. It is later revealed in the second season of the Toaru Majutsu no Index adaptation that Itsuwa and Uragami are two different persons.