Daihasei Festival Arc (Index)

The Daihasei Festival Arc (大覇星祭編) is a story arc in Toaru Majutsu no Index. It is September 19th, and the time has come for Academy City's annual Daihasei Festival, a sporting event that pits ability users from across the various schools of the city against one another in a series contests. For Kamijou Touma, this year's festivities have come with a twist as he finds himself having to foil a plot that could wreck the fragile balance between the worlds of science and magic.

The arc marks the 2nd time the Roman Catholic Church acts as the primary antagonist for Touma, it involves the church allowing Lidvia Lorenzetti to take over Academy City for the benefit of the church using the Croce di Pietro.

Increase of hostilities in the Magic side
With the destruction of their main fighting strengths: the Gregorian Chant and the Agnese Forces, as well as with the Amakusa Christians and Orsola Aquinas joining the Anglican Church (due to the events of September 8), and with the balance of power gradually shifting to the Science Side, the Roman Catholic Church has become severely weakened enough to allow the Mardi Gras—Lidvia Lorenzetti—to set up the Croce di Pietro in Academy City and take it over in secrecy. With the church succeeding in taking control of Academy City, would cause the power balance to shift to the church's favor since Academy City is the center and the entirety of the science side.

Lidvia's reason being in ensuring the welfare of the world as she views the Science side is usurping God's will, as well as her innate desire to conquer a difficult challenge, which is in this case taking over Academy City for the Roman Catholic Church and evangelizing its inhabitants under its dominion.

Oriana Thomson, an expert courier and master in eluding capture in the magic side,  is later involved with the operation, under the belief that having the Roman Catholic Church control Academy City, would create an absolute standard concept regarding goodness, due to it being governed by the laws of one unifying belief. Since the concept of good being dependent on a human's perspective towards it, which often cause tragedies since it becomes twisted due to the nature of humans. Oriana sides with the Roman Catholic Church since they are the most capable of achieving her goal, through the dominion of others.

Roman Catholic Church plans
The plan was for Lidvia Lorenzetti to activate the Croce di Pietro outside of Academy City during the Daihaseisai because of the stressed security for the event, while Oriana Thomson acts as a decoy for any magicians trying to stop them. For the plan to work, they made use of Croce di Pietro's obscurity and created a ruse regarding a fake artifact known as the Stab Sword that could kill a Saint in one blow, with this they are able to keep any Saints allied with any opposing factions at bay during their plan. The church furthered this deceit by leaking false information that Oriana was hired by Lidvia as a courier to transport the sword into Academy City, to be received by an unknown party. They also made sure that they distance themselves from Lidvia for the plan to work, as so to not attract attention.

Conveniently, the Roman Catholic Church's planning on capturing Academy City, has stifled the efforts of outside magical factions in entering Academy City to stop the "delivery" because it is an enemy territory, and would constitute as an invasion to both the already troubled sides. This forces factions to resort to only those who have connections in Academy City to enter the city to stop them.

Reaction of other factions
The ruse works as the Anglican Church is led to believe that the Lidvia is working with Oriana on their own to deliver the Stab Sword in Academy City, with the church also suspecting that Nikolai Tolstoy of the Russian Orthodox Church is the recipient of the delivery. Because of the danger posed to the balance of the magic side by the Stab Sword, Laura Stuart contacts the General Supervisor of Academy City, Aleister, to help with the situation. Here, she reveals to Aleister the Stab Sword and its use, the relevant parties involved with the deal, and the place where the deal would made, Academy City. As a response to this, Aleister allows Laura to send out operatives who have friendly relations with Academy City (more likely because of Kamijou Touma), due to the volatile politics involved with sending out magicians to operate in Academy City, as many other factions would want to get involved in the operation themselves.

Prelude
As with the agreement, Stiyl Magnus is to meet with Tsuchimikado Motoharu to handle the deal with the Stab Sword as they are one of the few members of the Anglican Church that has friendly relations with Academy City, while Kanzaki Kaori is forced to go on standby due to the nature of the situation. Back in England, Orsola Aquinas and Sherry Cromwell are tasked to search for information regarding the artifact in the British Library.

Meanwhile, Kamijou Touma has a bet with Misaka Mikoto, in which the student of the school which a lower score than the other is forced to do whatever the winner tells him or her to. Touma later competes and successfully wins a competition with his classmates, after seeing Tsukuyomi Komoe get insulted be a fellow teacher for her class' (Touma's class) poor academic performance. Meanwhile, Mikoto witnesses Touma's team's efforts in defeating their opponent with Index, and is actually worried at the prospect of losing to Touma.

After getting to a perverted incident with Fukiyose Seiri, who he sees naked; Touma later joins Index for a little snack, however, due to security issues Touma is only able to have Index eat after the next event he is, much to her frustration. Index decides to take her anger out on Touma, however, he is saved by the arrival of Mikoto who drags Touma away because he is the item that Mikoto requires for the Borrowed Item race that she is in. At the same time as this, Shirai Kuroko, still wheelchair-bound is with Uiharu Kazari, and sees Mikoto with Touma on a giant television screen, irritating her that he is with Mikoto, while Mikoto is being "unusually kind" to him.

Kamijou Touma's involvement
Touma later returns to the spot where he left Index, though he could not find her (since she was taken away by Komoe), however, while looking for her he discovers Stiyl and Motoharu talking and decides to investigate. Here, he discovers that a magician named Oriana Thomson was hired as a courier by Lidvia Lorenzetti of the Roman Catholic Church, and has infiltrated Academy City due to stressed securities, and is planning to deliver the Stab Sword to a recipient in Academy City. Stiyl and Motoharu explain to Touma why the magicians chose Academy City for the delivery, the reason why Kanzaki Kaori cannot be involved due to the nature of the spiritual tool being delivered. They also the reason that only magicians that have friendly relations with people from Academy City, such as Kamijou Touma can enter Academy City (under the excuse of simply visiting Touma), because sending out operatives from the magic side such as the Anglican Church into Academy City would attract other factions.

Motoharu later tells Touma on how the Stab Sword could kill a Saint, as well as the likely reason for the deal was to prepare for the war between the factions. Motoharu also explains to Touma on why he cannot involve Index into their mission, even though she would be quite useful for it. He states that due to the deal taking place, several other magic factions are observing the situation in the city using magic, since they are unable to intervene (for their own purposes) because the trade is happening in Academy City. Index is attributed by several magic organizations as the one to have settled (actually Touma) the magic side incidents happening occurring in the city, as her identity and presence is much more noticeable to magicians, as such they could track the deal and most likely, Stiyl, Motoharu and Touma's operations against it using Index, and use that as an excuse to rush into Academy City.

Meanwhile, Index is fed by Komoe after being left alone by Touma, and later agrees to wear to try on a cheerleading uniform to try and cheer for Touma. Back with Touma, he meets up with Himegami Aisa and Tsuchimikado Maika, who directs him to Index's whereabouts. Touma goes into a botanical garden and finds Komoe and Index; much to Touma's misfortune, the latter is indecent (as she was changing into her cheerleading uniform) with Touma accidentally seeing her. Index tries to bite him out of anger, but fails and accidentally kisses Touma on the cheek, which embarrasses her. To complicate things, Fukiyose Seiri arrives searching for Komoe for committee work, however, after seeing what Touma has gotten himself into she attacks him and later drags him away.

First Chase
While Touma is being dragged by Seiri, she comments on how he is somewhat restless and asks whether the festival is boring to him, worried that she is not doing enough as a committee member to make the festival more enjoyable. Touma denies that the festival is boring, still worried, Seiri demands Touma to tell her what's making him restless, though obviously Touma cannot tell her about the magic side. However, someone bumps into Touma which inadvertently pushes his face close to Seiri, much to her discomfort and later head-butts him. As a result, Touma later bumps into the chest of a blond woman wearing a poorly buttoned work uniform, carrying a large billboard covered in cloth. After being coerced by Seiri to not accept the woman's kiss as an apology, Touma shakes hands with the woman. Suddenly triggers Touma's Imagine Breaker and making him suspicious, she leaves quickly afterwards.

Touma pursues the suspicious woman while contacting Motoharu regarding the incident with the woman carrying the clothed billboard; he later tells Motoharu his location. The woman is Oriana Thomson who is aware that she is being followed by Touma, reports to Lidvia that one of the spells that they set-up was somehow negated. Though Lidvia is worried about this, she demands Oriana to perform a countermeasure, to which Oriana runs away from Touma to escape.

Touma tries to pursue her, though she nearly escapes his sights if not for the arrival of Motoharu and Stiyl, due to Touma sending his coordinates to Motoharu. With this, the three of them pursue Oriana after being identified by Touma, even then she is too slippery and has too much of a head start for them to catch up to her. However, Oriana's path is interrupted by a crowd of people, because of this she is forced to take a turn and go into an Autobus Maintenance Terminal. Touma, Stiyl and Motoharu continue their pursuit of her into the terminal, however, they encounter various traps set up by Oriana using her magic. This compels them to be careful in their movements, even with Touma using his Imagine Breaker to cancel Oriana's traps. In a lull in their chase, Motoharu asks Stiyl to apply his runes in the terminal and to be on standby. Motoharu and Touma continue to pursue Oriana before she gets away, plowing their way through her traps, however, because of this Oriana is able to put enough distance between them to lose their sights on her, and as such Oriana escapes from them. While escaping, Oriana bumps into students carrying a large pole for the ball tossing competition, and decides to use it as a means to draw Touma and the others away.

After finding one of Oriana's flashcards she used for magic, Motoharu creates a magic circle in order – the All-around Reality Circle, which works in a three kilometer radius – for them to find Oriana using the flashcard as a medium, using Stiyl as the magician to perform it. However, while using the searching spell, Oriana notices Stiyl and uses a counterspell on him. The counterspell causes Stiyl to be experience excruciating pain, this forces Touma to use his Imagine Breaker negate it. While recovering Stiyl, Motoharu and Touma discuss on how Oriana is able to create complicated magical spells, and how she was able to make use of Stiyl's lifeforce to create a counterspell, with this, Stiyl would experience intense pain if ever he uses magic. In the original light novel, Touma, Stiyl, and Motoharu expand their discussion to that of magic circles in general, how they are similar to grimoires, and how it relates to Oriana's type of magic.

The group decides to destroy the Oriana's counterspell Shorthand Origina las top priority, to enable Stiyl to use magic again. However, to be able to do is they needed to find it first, using a Divination Circle that reacts to counterspell. This basically forces Stiyl to use magic and experience pain again as so the counterspell would react to Stiyl's lifeforce in order for the Divination Circle to locate the counterspell Shorthand Original. Though reluctant in letting Stiyl getting hurt again, and after hearing Motoharu's arguments, Touma allows Stiyl to use magic in order for the counterspell to react. Stiyl later declares his displeasure with Touma being here with them instead being with Index, with this, Stiyl begins using magic.

Ball Tossing Competition Crisis
The spell works, though at the price of making Stiyl temporarily disabled. This angers Touma after seeing Motoharu's apathetic nature towards Stiyl's condition, however, he relents after seeing Motoharu himself bleeding after using magic to activate the Divination Circle. While trying to find the likely location of Oriana's Shorthand, they discover to their horror that it has been set-up in a middleschool.

With Stiyl incapacitated, Motoharu set-up a All-around Reality Circle for him to use when they finished destroying Oriana's counterspell Shorthand and leave him in the terminal. Meanwhile, Touma and Motoharu race to get to the middle school before the match starts, with the threat of the counterspell hurting civilians, Touma and Motoharu are forced to infiltrate the middle school by disguising themselves. When they enter the grounds, they soon discover that the middle school is forced to compete against Tokiwadai Middle School with Misaka Mikoto already seeing Touma present. They are forced to be extra careful as not to get caught in the crossfire during the competition, as they search for the poles used in the competition, which Motoharu deduces to be the most likely place the counterspell Shorthand has been set-up.

The match starts and chaos ensues on both sides while Touma and Motoharu check the poles one-by-one for the Shorthand. However, due to the carelessness of the competitors of the other middle school, one pole begins to fall which forces Touma and Motoharu to act quickly, in the fear that the pole may have the counterspell Shorthand. With the help of Motoharu, Touma is able to save a girl from Tokiwadai from the pole's path, and instead puts him in danger. However, he is saved by Mikoto's intervention, who used her Railgun to move the pole. She appears before Touma and demands to know why he is here while attacking him if with here electricity, though obviously to no avail. However, their argument is interrupted after Touma sees Mikoto trying to lean on a pole, which has a piece of paper stuck on it. Touma suspicious of this, tells Mikoto to move away from the pole though Mikoto does not understand, with Touma unwilling to divulge information regarding the magic side to explain to her. She later begins to misunderstand Touma's intentions even more after negating an attack from a middle school student, she blushes and becomes restless because of this which Touma sees as a sign that she has become affected by the counterspell Shorthand after touching it. This forces Touma to dash forward towards her and make her lie on the ground, as so he can check on her condition. Mikoto becomes even more reddened because of this and freezes herself because of him, to which Touma sees as a sign of the counterspell and calls Motoharu over to the pole where the paper was placed.

However, this was a mistake, as he discovers that the piece of paper is not the Shorthand. Shortly afterwards, Fukiyose Seiri arrives and stops the match, demanding to know why Touma is in the grounds while leaning on a pole. Suddenly, Seiri is blown down by an unknown force and collapses to the ground. The pole had the Shorthand which reacted to Seiri touching it; Motoharu arrives and tells Touma to use Imagine Breaker on Seiri quickly as she is not a magician and is much more vulnerable. Seiri is later taken away by parademics and is later sent to the Heaven Canceller's hospital. Meanwhile, Touma strikes the pole with his right first where the Shorthand was placed, and declares that he will destroy Oriana's illusions with it.

Battle against Oriana Thomson
Touma and Motoharu slips away from the school grounds afterwards and contacts Stiyl who has recovered in the terminal to check if he can now use magic, to which Stiyl confirms. Motoharu reports on how a civilian was hurt during the search, which is the reason why they were able to slip away. Stiyl is later tasked to perform the All-around Reality Circle that Motoharu set up to help them guide to Oriana's whereabouts. Oriana notices this as well and begins to move, meanwhile, Touma and Motoharu follow her closely through Stiyl's instructions. They keep up to her up until she arrives on a bus stop, and gets on an autobus, worrying Touma that she might get away. Motoharu is however unworried of the situation, after confirming that there are no other people are in the bus, he contacts Stiyl to use one of the rune cards he has attached to the auto bus. The rune card activates and fire immediately erupts from it, making the bus explode.

Oriana survives however, after using her magic and teases Touma and Motoharu. Touma notifies her that her spell hurt an innocent civilian who has nothing to do with magic, Oriana is aware of this and says that she did not intend to hurt Seiri. She then tears another flashcard and activates another spell. Almost immediately, Motoharu collapses after experiencing extreme pain; Oriana informs Touma that it works only to those who are injured, even then, Touma tries to use Imagine Breaker on Motoharu to no avail.

Kamijou Touma vs. Oriana Thomson
Angered by this, Touma tells Oriana that he does not know nor care about the Stab Sword or how it'll affect the world, however, since its existence causes harm on people, then he'll destroy it with his fist, and says that she should stop playing with people's lives.

Touma charges towards Oriana, though she responds to this by using Shorthand to summon an ice wall between them, which Touma easily dispels. However, Touma is caught off-guard by Oriana who uses wind to make a small cut on his cheek; Touma becomes worried because of this since Oriana could use another Shorthand that had the same effect on Touma earlier. However, Oriana attacks Touma with another spell, which suprises Touma as to she did not use the spell that made Motoharu unconscious. Seeing his surprised look, Oriana says that she doesn't like using the same over and over again. Oriana keeps attacking and overwhelms Touma completely.

With only knowing that her magic works by using colors that do not correspond to its name (such as the world blue is colored red) to create different effects, Touma is unable to gain the upper hand. In the novels, Oriana tells him how not only the symbols and the colors are required, but also the angle of which she rips the flashcard (which Touma predicted). She also tells him how she cannot use the same spell twice once it has been used.

Finally, Oriana pulls out another flashcard, declaring that Touma will die if he moved from his position. Though deterred at first, Touma quickly charges towards Oriana which surprises her. Suddenly, vacuum blades spring forth from the ground which would cut Touma, however, he is able to dodge and can easily negate them using the Imagine Breaker. Oriana surprised on how Touma's right hand is strong enough to negate the spell, tries to use another spell to attack. Touma however, negates it as well after predicting that similar attacks will not come from the same direction (novel). With this, Oriana is completely caught by surprise, which enables Touma to come into range and punch her and knocking her down.

The force of Touma's punch unbuttons Oriana's working uniform, she is however still conscious, and retreats quickly shortly afterwards, leaving her package behind, which surprises Touma. She informs him that it is not over, and later tells him that the effects of the spell on Motoharu would last only 20 minutes, before leaving.

The Stab Sword Ruse
Touma retrieves Oriana's package, and is told by Stiyl that with Touma's power he can destroy the Stab Sword. Touma is however concerned on the political implications of destroying the artifact, though Stiyl states not to worry about that as the Roman Catholic Church will be in trouble if they were to attack Academy City. With this, Touma begins to unwrap the white cloth, expecting to see the sword, however, to his surprise it is revealed it is actually a billboard all along.

Meanwhile, Oriana holds a conversation with Lidvia to report her progress, and that the true nature of the Stab Sword has been revealed, while changing her clothes as well. Lidvia is somewhat worried, though Oriana calms her down and states that she will finish the job and not let anybody get in her way. Back in Necessarius headquarters, Laura discovers that the Stab Sword never truly existed and that people came out with their own explanations about and legend regarding the artifact, since they did not know what purpose it had. Laura discovers the true purpose of the artifact is that it is not a sword but a cross and is called the Cross of St. Peter, or the Croce di Pietro. Though genuinely surprised by this as the deal within Academy City has changed drastically, Laura later intends to use such a knowledge in her own favor.

Back in Academy City, Stiyl, Motoharu and Touma discuss the situation regarding the Croce di Pietro. They discuss that the cross was erected on the tomb where St. Peter was buried, and on that land became the Vatican City State, the capital of the Roman Catholic Church. However, they explain to Touma that where ever the cross was erected, it would become the dominion of the Roman Catholic Church regardless, even if it is Academy City. They continue to explain that due to the power of the cross, any event even if it is unfortunate will become beneficial to the Roman Catholic Church, this effect would cause people to become happy regardless of the cost, fairness or burden. Worst of all, since Academy City is the center of the science side, the Roman Catholic Church taking control of it will significantly tip the balance of power to their favor. Stiyl confirms Touma's suspicion that the true nature of the deal was that the Roman Catholic Church taking dominance over the Academy City and the world.

With this, their mission now was to prevent Oriana Thomson and Lidvia Lorenzetti from using the Croce di Pietro to take over Academy City.

Interlude
Touma meets up with Index (to distract her) while Stiyl and Motoharu go look for more information; they later goes to a restaurant for lunch with his parents. Here, they also discover that his parents are with Misaka Mikoto and Misaka Misuzu, her mother much to their apparent surprise.

After lunch, Touma is forced to run away from Misaka Mikoto and Shirai Kuroko's wrath after they see Touma and Index in a perverted situation, mostly due to Mikoto's misunderstanding.

Meanwhile, Stiyl is conversing with Orsola Aquinas and Sherry Cromwell on the phone for more information regarding the Croce di Pietro. Stiyl however, disconnects from them shortly after both Orsola and Sherry start arguing. Komoe later arrives and regards Stiyl's smoking disapprovingly, knowing that he is underaged as well as smoking is against the rules, she tries to lecture him and later tries to take away his cigarette packets, albeit poorly while Stiyl simply ignores her. Meanwhile, Himegami Aisa observes all of this becomes worried for the both of them and meets up with Touma so that he could help them. When they arrive, Touma sees that Stiyl is simply teasing Komoe and says to Aisa that there is no trouble at all.

Their troublesome situation is suddenly interrupted by Stiyl leaving after receiving a phone call, and with Motoharu contacting Touma, with information regarding Oriana Thomson. With this, Touma departs quickly, with him asking Aisa to restrain Komoe before leaving.

In the anime adaptation, Stiyl and Touma depart together after Touma receives Motoharu's message.

Second Chase
Meanwhile, Touma and Stiyl regroups and tries to meet up with Motoharu so Stiyl can activate the searching spell for Oriana Thomson. However, due to certain circumstances, Motoharu is unable to meet up with them. With no other option left as Oriana is getting away, Motoharu is forced to perform the magic spell himself despite being an esper as well, despite Touma's protests, he and Stiyl are tasked to follow Motoharu's instructions in trying catch up to Oriana. At the same time as this, Oriana notices Motoharu's spell and decides to take her next step.

While Touma and Stiyl are trying to find Oriana using Motoharu's instructions, Motoharu suddenly discovers Oriana suddenly changing routes before getting his communication with Touma and Stiyl cut-off. Stiyl then discovers that even if Oriana knew that she was being tracked by a spell, she wouldn't know the distance where she wouldn't get tracked anymore, therefore the most logical solution for her is to eliminate the searching spell herself, meaning she would go after Motoharu. With this, Touma and Stiyl remain helpless as an injured Motoharu battle Oriana on his own.

Tsuchimikado Motoharu vs. Oriana Thomson
Motoharu is ambushed by Oriana Thomson while he was tracking her. With injuries previously incurred by Motoharu, as well as the recent injury he sustained from performing the searching spell on Oriana, Motoharu's odds are stacked against him as he is forced to fight alone with his injuries as well as without the use of his magic. With them declaring their magic names, they do battle, however, Motoharu is predictably overwhelmed despite his physical skill by Oriana's combination of magic and hand-to-hand combat.

Motoharu is later cornered by Oriana and is severely injured, though with no desire to back down, Motoharu creates a ruse utilizing the probability that Oriana has little knowledge regarding Eastern magic. Here, Motoharu deactivates the barrier Oriana set up in order to further his deceit, and lies to Oriana that he used a spell that contacts the saint Kanzaki Kaori as she can be put into actions, as the Stab Sword is threat is non-existent as well as her having a friendly relationship with Academy City, she has no reason to not enter the city to assist her comrades. To force Oriana to immediately run away instead of killing him, Motoharu smashes the rubble on the floor as so to force dust up in the air to reduce visibility. With unknown variables to work with, Oriana is forced to retreat and not to engage Motoharu again in battle as to not take any chances.

A seriously hurt Motoharu later contacts Stiyl and Touma, and informs them the most likely route Oriana would take.

Accidental Firing
While trying to escape, Oriana accidentally bumps into Tsukuyomi Komoe who then bumps into Himegami Aisa, spilling the liquid she was carrying on her shirt. Though wary of attackers, Oriana calmed down after seeing Komoe and Aisa, and apologize to them. However, Oriana suddenly sees the Walking Church cross necklace that Aisa is wearing to prevent her powers from working. Believing her to be an operative of Necessarius, Oriana attacks Aisa with a spell in front of Komoe. She leaves shortly after. Meanwhile, following Motoharu's instructions, Touma and Stiyl try to follow Oriana's route to catch up to her. They however, are distracted by a crowd gathered on a spot, at the same time as this Stiyl comments on how he smelled the scent of blood. Here, they discover much to their horror, which Aisa has been attacked and is now severely injured. Komoe while covered in Aisa's blood confirms Stiyl's suspicions that Oriana was the one who attacked Aisa, after mistaking her for a member of Necessarius.

After dispersing the bystanders, Stiyl notices on how Komoe is trying to perform the magic healing ritual she learned from Index. With this, Stiyl decides to help Komoe with the ritual even though he has little knowledge regarding it. Touma, although reluctant in leaving behind Aisa is forced by Stiyl to continue on and search for Oriana himself. Before leaving, Touma leaves Aisa's life at the hands of Stiyl, and later promises to go her room in the hospital before the Night Parade begins, with Aisa hearing it during a small glimpse of consciousness.

End of the Chase
Touma later loses Oriana's trail and is forced to contact Motoharu for assistance. Here, they discuss on why Oriana disregarded the inherent danger of exposing herself by moving around Academy City, even before they chased her when the Stab Sword and the deal with it didn't exist in the first place. Obviously with her having a reason to move around, Motoharu asserts that her actions may have something to do with looking for the conditions to activate the Croce di Pietro.

Touma later forwards information to Motoharu regarding the cleaning of the storage room for the Croce di Pietro, and on how the workers were careful not to expose the artifact to light during the cleaning. Seeing this as one of the potential conditions to activate the Croce di Pietro, they later conclude that the most probable way of activating the artifact, after eliminating the possibility of using the artifact during the day, and after the report that one of the workers of the artifact were trying to divine the stars, that starlight is needed to activate it, specifically the light of a constellation in the sky. The only thing they need to do now is to figure where Oriana and Lidvia would set up the Croce di Pietro, before sunset afterwards the stars will begin to appear.

After distracting Index one last time, Touma continues to search for Oriana until he receives a call from Stiyl who indicates that he has successfully healed Aisa and has sent her to a certain hospital, much to Touma's relief. Their conversation is later interrupted by Komoe's incessant agitation of his person, grateful that he saved Aisa. Before hanging up, Stiyl instructs Touma to call Motoharu again, hinting that he may have found some clue. After meeting with Motoharu again, they discuss the flaw on their theory that Oriana and Lidvia are using constellations to activate the Croce di Pietro, since records show that the cross is incompatible with the autumn constellations.

However, Orsola Aquinas accidentally contacts Motoharu's phone. Here, her report confirms their theory that the Croce di Pietro uses the light of the constellations to activate. However, Orsola adds that the Croce di Pietro can be activated regardless of the seasons, as the conditions that are required is for the user to learn the characteristics of an area and use one of the constellations which best corresponds to the aforementioned area. This would theoretically mean the Roman Catholic Church could take over and control any part of the world. She later tells them the most likely locations where the Croce di Pietro would be activated in Academy City on September 19th.

Into the battlefield
Stiyl manages to escape Tsukuyomi Komoe's grasp and meets up with Touma and Motoharu again. Here, they have already determined the best possible position for the Croce di Pietro to be activated: at School District 23; intending to catch both Oriana and Lidvia there. Knowing full well of the tight security measures in the district, Motoharu calls Aleister Crowley unbeknownst to Stiyl and Touma, to modify the security a little and allow them to slip in.

With the confused security, the trio is able to infiltrate the location where the Croce di Pietro would most likely be used. However, while climbing a barrier Motoharu gets affected by one of Oriana's shorthand spells placed on the barrier, due to his vision being blurry due to the injuries and pain he received. With this, Touma and Stiyl is forced to carry on without Motoharu, and later destroys the shorthand that Oriana left using the Imagine Breaker, before finally entering the location where Oriana awaits there final battle.

Final battle
The battle begins with Oriana creating a barrier in their location, to block communication from the outside world. Here, Stiyl trades magic attacks with Oriana, however it has little to no effect on her, and is later beaten down by Oriana due to his weak frame. Touma faces Oriana alone, and is easily overpowered by her superior physical skills in combat. Touma reaffirms to Oriana that he will no longer allow her to interrupt the Daihaseisai and stop the Croce di Pietro, Oriana is amused by this and states that the artifact will give happiness to both sides. Touma agrees that getting happiness is good, however, he does not care about the sides and states that the only thing he cares about is to keep the Daihaseisai, and the thing that everybody is working hard for will be trampled by the cross. Oriana is still unfazed by this however, and with her resolution, Touma declares that he will break her illusions.

The battle continues, with Touma trying to fight Oriana alone, however, he is unable to find an opening to even remotely damage Oriana. Stiyl however regains consciousness and summons Innocentius to attack Oriana, even though Touma was in the way, much to his chagrin. However, Innocentius' arrival gave Touma an opening, allowing him to damage Oriana, and with her getting befuddled by Touma and Stiyl's confusing teamwork. She is unable to predict their attacks and is later beaten down by both Touma and Stiyl.

Kamijou Touma vs. Oriana Thomson II
Not wanting to give up her dream of having an absolute standard in the world, Oriana manages to stand up and use another spell, severely injuring Stiyl after kicking Touma out of the way and dispelling Innocentius. With Stiyl down for the count, Touma is left alone to fight Oriana Thomson to battle. Here, Oriana states that using the Croce di Pietro, the Roman Catholic Church can fulfill her desire: to merge and standardize all viewpoints in the world. To Oriana it doesn't matter whether it is the Roman Catholic Church or Academy City, as long as there is only a single viewpoint, she laments on no matter how much good she does, the conflicting nature of humans would often result in her actions being turned bad. However, Touma states that she is only making excuses, by allowing the Roman Catholic Church to set the standard she is basically giving up on trying to do good for others. Touma continues by saying that no matter her goal, attacking Academy City for the use of the Croce di Pietro does not justify her for using people for other's to use as a stepping stone.

With her illusions broken, Oriana becomes dispirited and decides to end their battle once and for all. She uses up all of her flashcards to create a very powerful against Touma. Seeing this, Touma steps forwards to dispel it, however, it was a trap by Oriana who knew he would dispel her attack. The spell has an extra effect and blasts against Touma's body. The attack renders Touma unconscious for a moment, giving Oriana an opening an attack, however, after remembering the efforts of the people he know who wants the Daihaseisai to be a success, regains consciousness and charges towards Oriana. He then tries to exchange fists with Oriana, with him being able to connect, giving a powerful blow to Oriana's face rendering her unconscious, and finally beating her.

Night Parade
With the barrier dispelled after Oriana's defeat, communication from the outside can be achieved now. Stiyl orders Touma to force Oriana on finding Lidvia Lorenzetti and the Croce di Pietro and destroy it. However, they are suddenly addressed by Lidvia Lorenzetti herself, who tells them that the Croce di Pietro will soon activate and that Academy City will soon be under the Roman Catholic Church's control. She indicates that the Roman Catholic Church would take care of them and their injuries if the church would benefit from it. Lidvia continues by saying that she and the Croce di Pietro are outside of Academy City, and that the range of the artifact could cover an area way beyond Academy City.

Here, it is revealed to them that Oriana was simply a decoy for any pursuers, while Lidvia would wait for the appropriate time to activate the Croce di Pietro, already knowing the most suitable observatory for the cross to gather the light from constellations. Lidvia laments Oriana's failure, however, with the cross close to activation, her downfall would become beneficial to the Roman Catholic Church as well, and brags on how the Science side will finally bow down to God. With only single card to play left, Stiyl tells Touma to contact Motoharu to use the All-around Reality Circle to calculate Lidvia's location, and with his communication spell would then later contact the forces outside to take her down.

However, Lidvia states that it is too late. With only a couple of minutes left before the appointed time of the activation of the cross, Touma notices something, and calls Motoharu to confirm how far the reach of the cross would be, to which he states it would 1,700 meters away from the northern point of Academy City. Without giving pause to explain it to Motoharu, Touma searches frantically in his cellphone for information, and later drops it. With this, Lidvia says that it is the end, to which Touma agrees that it is the end and the end for him as well, as he says that he couldn't his promise to his classmates even though he has broken her illusion.

With that, a surprised Lidvia discovers that the Night Parade has begun, covering the night sky and blocking the starlight that is required for the Croce di Pietro to work, with the artificial lights of fireworks and neon. With this Touma states that she has completely underestimated the people who were trying their best to make the Daihaseisai a success; he continues by saving that she should destroy the Croce di Pietro and never bother Academy City again. Lidvia however, refuses, to which Touma says that she would be running around just like in a sports festival, as it is indicated that Motoharu can use the All-around Reality Circle to search for Lidvia and contact the outside forces to help them find her, and finally settle the incident.

Magic side
Lidvia Lorenzetti later escapes 14 hours later from the factions that were contacted by Stiyl; she is with the cross in a private jet. Here, she is disappointed with the events that have unfolded and is most surely admonished by the Vatican for her failure. However she is fine with that fact, and is willing because of her personality of desiring harsher obstacles because it the joy is greater when overcoming; with it she is determined to settle her case with the Roman Catholic Church, save Oriana and then attack Academy City. Her brooding however, is interrupted by the voice Archbishop of the Anglican Church – Laura Stuart.

Lidvia believes that Academy City helped the Anglican Church apply the spiritual tool that Laura uses to communicate to her before taking off from Japan. Laura begins to tease her regarding her personality, though Lidvia is quite proud of it and thanks God for the obstacle presented to her. Suddenly the jet's door bursts open and Lidvia and the Croce di Pietro begin hurtle downwards to the ground. While falling, Laura proposes to her that if Lidvia give up on the Vatican's teachings and submit to her, she will save her without harm, though Lidvia refuses to offer, to which Laura states she should fall with the cross that is coming of hers. The Croce di Pietro is falling down towards the earth, though Lidvia is confident she could catch it, even if the force of the falling cross would injure. However, she is later surprised by the discovery that the pilot of the jet is falling as well. Laura challenges her to choose whether to save the cross or save the pilot, and once again gives her a proposition of help if she submitted to her. Seeing this as a challenge, Lidvia rejects the offer and decides to save both the cross and the pilot, she is then crushed twice by the impact of the cross and the pilot.

Science side
Touma, Stiyl, Motoharu and Oriana are later discovered by the security of School District 23, with them being admitted into a certain hospital, where his parents await for his recovery. Here, Touma is scolded by Index for going all out again and engaging himself in a battle that involves the fate of the world and Academy City, and is bitten by Index for all his trouble.

Misaka Mikoto with Shirai Kuroko later visit Touma, and after being angered by Index's presence alongside Touma, informs him that Tokiwadai Middle School as greatly surpassed his school in points, which means that he has lost the agreement they made. Touma however, tries to negotiate with Mikoto though she simply ignores him.

The next day, Index wakes up in the bed of Himegami Aisa who has recovered from the attack. Here, Aisa laments on how she caused trouble for everyone, and made Touma do something reckless. Index however disagrees, and states that Touma is happy to be with Aisa, she continues (in the novel) by saying that even though Touma has a lot of people he protects, he will never see Aisa as someone who is troublesome and will always try to protect her regardless. Aisa asks why Touma keeps fighting, to which Index states that she doesn't know, though the only answer she got from Touma is that he is doing it for himself, and concludes that maybe for Kamijou Touma that is happiness for him. After that moment, Touma who is arguing with a recovered Fukiyose Seiri enters Aisa's ward, something that Aisa looks forward to.

Implications in future events
With the failure of Oriana Thomson and Lidvia Lorenzetti (who are later detained in London) and with the Croce di Pietro lost, the events of September 19 would force the Roman Catholic Church to opt for the total destruction of Academy City instead of capturing, by reviving an ancient weapon of the church, The Queen of the Adriatic Sea.

Meanwhile, even with the events of the Croce di Pietro being settled with the help of Kamijou Touma. With the increasingly aggressive movements of the Roman Catholic Church, Aleister Crowley becomes more restless while inspecting the Sister clones distributed around the world. With the Imagine Breaker still unstable, Aleister is forced to consider the possibility of taking action personally and prepares his own weapon, the Blasting Rod.

Trivia

 * This arc would mark the first time an arc covers two novels.