Deep Blood Arc

The Deep Blood Arc (編) is a story arc that occurs in the Toaru Majutsu no Index storyline. It introduces Himegami Aisa and her ability "Deep Blood", which is central to the plans of Aureolus Izzard, a powerful alchemist and former partner of Index.

Along with the Angel Fall Arc, the anime adaptation of this arc is one of the most heavily modified in the Toaru Majutsu no Index anime series.

Aureolus Izzard
Three years prior to the start of the Toaru Majutsu no Index storyline, Aureolus Izzard was an extremely talented magician of the Roman Catholic Church, whose job was to write grimoires. Believing that he could save more people without the constraints of the Roman Catholic Church who used the grimoires as their trump cards, Aureolus went to England where magic and witchcraft was most rampant. Here, he discreetly worked with the Church of England and later met Index, holder of the 103,000 grimoires, and became partners due to their work.

Seeing Index bear the weight of the 103,000 grimoires but still kept on smiling, here, he sees the limits of his knowledge while trying to save her. Seeing that he couldn't save Index, Aureolus lost faith in his abilities and his ability to save anyone. As such, he goes against the Roman Catholic Church, in order for him to search for a way to cure Index.

Eventually, Aureolus determined that the way to save Index was through using a being that was beyond human—vampires.

Himegami Aisa
10 years before the start of the series, a remote village in Japan gets attacked by a vampire. The vampire turns every one residing in the village as a vampire, except for Himegami Aisa. The vampires act and look like regular humans, however, they were attracted to the blood of Aisa. Because of this, they were all killed by her ability, called Deep Blood; her ability attracts vampires to her, however, the vampires themselves are killed instantly because of her blood.

Aisa was horrified of her abilities, as many people she knew from the village died because of her. Because of this, she goes to Academy City, and enrolls in Kirigaoka Girls' Academy, believing that they can help her remove it, however, they were unable to.

Cult of Science
Misawa Cram School, a preparatory school in Academy City, originally intended to spy on the workings of the Power Curriculum Program, goes rogue from its original purpose and transforms into a cult of science. Aiming to replicate rare abilities and transfer them to other people, they abduct Himegami Aisa who has a rare ability, though they themselves were unaware of the details of her power.

However, Aureolus Izzard, who has now perfected his Ars Magna takes over the school, complicating Academy City's response to the situation. He then controls the minds of its inhabitants and puts a seal on the building making it his fortress. Himegami Aisa allies herself with Aureolus, after she realizes that Aureolus would need her powers to save someone. She goes outside the school from time-to-time as so she can attract vampires with her blood.

Their relationship, however, is misinterpreted as sort of an unlawful imprisonment of Aisa by Aureolus instead of a partnership between them. This situation, would later be used as the reason for the Church of England and Kamijou Touma's involvement.

Academy City's Response
Originally, Aleister Crowley simply planned on Academy City getting rid of the cult itself. However, since the arrival of Aureolus Izzard and his taking over of Misawa Cram School, the situation has become complicated, as the science side cannot simply intervene with the actions of the magic side, else it will disrupt the balance between the two sides.

Aleister invited the Roman Catholic Church and the Anglican Church to send in representatives to take down Aureolus, as such the Thirteen Knights and Stiyl Magnus was dispatched as the respective representatives for their churches. However Aleister did not tell either side there will be forces apart from themselves, leading the Thirteen Knights and Stiyl entering separately and resulting in the s of at least one of the Thirteen Knights.

Aleister suggests to Stiyl to use Kamijou Touma, the Imagine Breaker to aid him in the mission, citing that he is simply a level 0, a powerless person and that he will not be able to leak information from both sides. Stiyl highly doubts his reasoning as Touma's power defies understanding of both sides (or so he thinks) and no way is Touma a true "powerless" Level 0 like Aleister claims. It is even explained that it is almost like Aleister is deliberately giving Touma trials to overcome like the Saints of ancient times.

Prelude to Kamijou Touma's involvement
Touma tries to adjust to living the of the old Kamijou Touma after the events of the Index arc. Although he struggles, he manages to fool Index in his ruse, and is fully aware that Index's feelings for him is that of the old Touma.

Despite this, Touma tries to continue on with his unusual, living as someone else entirely for the sake of Index. His ruse is put to the test when Touma meets one of his friends from A Certain High School, Aogami Pierce who is curious regarding Index.

Touma had a little difficulty in trying to present himself to Aogami, however, he manages to fool him; Aogami however, is apparently too preoccupied with Index being with Touma. Unfortunately, Aogami's curiosity of Index got the best of him, annoying her. This forces Touma to calm her down, as he too provoked Index.

Meeting with Himegami Aisa
After much trouble, Touma decided on going to a rather crowded restaurant for Index, with Aogami (and Motoharu as well in the anime adaptation) tagging along. They are later forced to sit with a peculiar girl wearing a or shrine maiden outfit. Touma becomes wary of her, due to her queer appearance and becomes a bit hesitant to approach her.

He is however, reluctantly pulled into acknowledging the girl, after she states that she has spent her all of her money. Not knowing what to do, they decide to play in order to find out who should talk to her. Naturally, Touma loses. Having to humor her, Touma discovers that the girl has used all her money up for hamburgers and would be unable to have enough money for the train fare back home.

After much frustration on her side, Touma eventually suggests for her to borrow money from someone. This suggestion however, piques her interest and looks upon Touma and the rest of the gang for such a money to borrow from, much to their surprise. Eventually, Index herself becomes irritated at her begging for money and off-handedly insults the girl being a shrine maiden. The girl however, corrects Index, and states that she is not a miko but a magician. This however, provokes Index even more, demanding Aisa to show some evidence regarding her claim. She then states that she should at least pretend to use an oriental-style magic since she looks like a shrine maiden.The girl however, disregards Index's arguments and simply states that she will be "that", which further infuriates Index.

Touma tries to calm the situation down, but is berated by Index for allowing the miko to get away with calling herself a magician, while she had to go to the trouble of proving the existence of magic to him. Their argument however, is suddenly interrupted by the sudden arrival of several suspicious-looking men, who has apparently arrived to take the girl back home. Despite Touma's suspicions, he cannot do anything about it. However, the girl relieves him of his worries and tells him that they are simply her cram school teachers. They and Aisa later leave much to their consternation.

Kamijou Touma's involvement
After leaving the restaurant and Aogami, Touma and Index comes upon an abandoned cat, and has apparently come to like it, and has already named it Sphynx. Touma strongly disapproves, however, the cat runs away, to which Index tries to go after it until she somehow notices a magical disturbance, leaving Touma alone.

It is revealed that Stiyl Magnus used his magic to make a distraction for Index just so he can meet with Kamijou Touma. Despite some trouble at first—to the point of having to himself from Stiyl attacking him—Touma manages to successfully lead Stiyl into thinking that he is still the same Kamijou Touma from before.

With Touma's full attention—to which made Stiyl somewhat suspicious of his perceptiveness—Stiyl explains that a girl has been in imprisoned in Misawa Cram School, and it up to him to free her. He notes on how the school has become a phony religious cult devoted to Science Worship. However, Stiyl states that whatever they are doing is no longer relevant as they have been taken over by an alchemist. Here, he states that the alchemist's goal was to abduct Deep Blood, a being who has the power to kill an being of legend, that even magicians don't even know exists, vampires. Stiyl states that the alchemist must be after the fact that since Deep Blood can kill vampires, by default vampires exist as well—a highly sought after being in the magic side.

Having enough of Stiyl's esoteric ramblings, Touma asks what he wants from him, to which he states that Touma is coming to aide him in rescuing Deep Blood. Before leaving him, however, he states that the Church will take away Index from him if he does not comply.

Preparation for the assault
With Touma's recruitment, he is forced to take part in Stiyl's mission. Touma later returns to his dormitory to remind Index that he'll be late coming home. Also, here he finds Index and allows her to keep the cat she found a while ago, despite his protests.

Touma later discovers that Stiyl is planting runes of Innocentius outside of his dormitory room in order to protect Index from any one who may want to take her. During their short conversation, Touma discovers that Stiyl has an infatuation towards Index, which he tries to vehemently denies. Touma however, seeing his denial simply drops the subject.

Later, the two of them discuss their opponent, the alchemist known as Aurelous Izzard, and the captive Deep Blood known as Himegami Aisa. Here, he states that Aureolus Izzard has obtained the objective that the all alchemist pursuit and that is to model the world in his mind. More specifically, Aureolus knows and understands the laws of the world and can imagine the world in his mind, and in turn able to bring out that imagined world into the real world. In short, Aureolus Izzard had the ability to will that simulated world into reality.

Into the battlefield
Upon entering the building, Stiyl and Touma notice the eerie normalcy of the people inside the building. What's more, the people inside doesn't seem to notice their own queer presence in the building. Stiyl later explains to Touma that there is a seal that surrounds the building, separating people from a sort of inner side and outer side, as such they the students are unaware of the corpse inside the building, and when to objects from the outer side and inner side cross the same space, they will not interact and only slightly distort space. Stiyl also indicates that Touma's Imagine Breaker cannot destroy the spell unless he touches the core that is setup in the school for that boundary to take effect. As such they are trapped inside the school after going in.

At the same as this they discover the corpse of one of the Thirteen Knights of the Roman Catholic Church, here Stiyl explains that they may have been annihilated by Aureolus.

Although Touma is shocked to find a corpse, he tries to move on, as he is in a battlefield, with Stiyl's insistence, although he too is slightly unnerved by its presence, and sends the corpse off as a priest. Here, Stiyl notes that he has another reason to fight now.

First Assault
Touma and Stiyl are forced to use the stairs, seeing as they cannot interact with the objects on the other side of the barrier Aureolus made. While searching for the secret rooms, Touma checks to see if he can use his phone to interact with the other side of the coin. It works, as he is able to contact Index without a problem, and tries to make a suspicious excuse to Index. Stiyl however, chastises Touma for this as they are in the battlefield. He reminds Touma that the difference between him and Touma is that Touma succeeded in saving Index. Stiyl continues by saying that several other people have wanted to be in the position where Touma is right now—with Index. Touma takes this to heart, and is reminded by the fact that the Kamijou Touma who saved Index isn't him but the one who had his memories erased.

Gregorian Chant Replica
Still trying to search for the secret room, they later come upon a cafeteria filled with students, blissfully eating away. The students however, suddenly stopped doing what they were doing previously, and have apparently notices. Stiyl notes that the cafeteria had an alarm system that forces the students into "their" side. Here, the students began chanting a spell, which creates multitudes of magical spheres to attack them. With so many attacks to handle, both Stiyl and Touma decide to make a run for it.

As they are being chased by the spheres, Stiyl explains that Aureolus was probably able to wield the 2,000 students of Misawa Cram School as substitutes for the 3,333 monks that are normally used for the grand spell, a Gregorian Chant Replica. Stiyl notes that they need only to destroy the "core" that is controlling the students simultaneously in order for them to stop the spell. Stiyl and Touma however, are later separated because of the students' attack and Stiyl using Touma as decoy.

Touma later comes upon a girl who once again tries to use the Gregorian Chant Replica, however, she is hurt and is injured during her chant, due to her being an esper. However, due to Aureolus' control, she is unable to feel pain. Worried, Touma tries to stop her, but the girl faints afterwards, apparently overwhelmed by her own injuries. While preoccupied with the girl, Touma is nearly caught on by the spheres of magical energy of the Gregorian Chant. It surrounds him, but they later stopped moving and dissipates afterwards.

Immediately after, Touma meets with Himegami Aisa again.

Stiyl Magnus vs. Aureolus Dummy
Stiyl is shown to have detected the mana where the core of the synchronization of the Gregorian Chant replica is and has successfully destroyed it, which inadvertently saves Touma from the spell surrounding him. Immediately after, he is confronted by Aureolus Izzard himself who has apparently lured Stiyl intentionally with the Gregorian Chant Replica. After throwing a couple of insults towards Aureolus, he demonstrates his abilities to him, turning things into gold instantly, Limen Magna, and demands Stiyl to summon Innocentius so he can test his Limen Magna on it.

Stiyl however, refuses and belittles his Limen Magna, stating that using Innocentius would be overkill. Angered by Stiyl callous disregard of his ability, Aureolus attacks Stiyl with his Limen Magna, successfully hitting him several times. However, Stiyl is apparently unhurt by Aureolus, much to his surprise who continues attacking. Finally, Stiyl reveals to the troubled Aureolus that he is simply a dummy created by the real Aureolus. Stiyl quizzes the unbelieving dummy on why he studied Alchemy. Here, the dummy states that he wants to discover a way for a human to ascend higher without humans losing their humanity. However, Stiyl points out the flaw in his reasoning, asking the reason why he needed the vampires, who are beings that surpass humanity. With this, the dummy's world collapses entirely.

Suddenly, Stiyl appears behind him, apparently using a mirage all along during their conversation. Immediately after, Stiyl uses his fire sword, and hacks some of the dummy's limbs off. With this blow, the dummy goes wild, attacking things using his Limen Magna seemingly at random, completely destroying the floor and making it to molten gold. During all the commotion, the dummy took the time to run away from Stiyl.

Kamijou Touma vs. Aureolus Dummy
Meanwhile, Touma meets with Aisa again, and helps him give first aid to the girl who was injured for using magic with her knowledge in blood flow. Touma and Aisa converses a little, with Aisa still insisting that she is a magician. Touma later suggests to call the ambulance as he needs to go back into the "battlefield", and says to Aisa to go home too as she has been captured, which confuses Aisa.

Before Aisa can explain herself, the Aureolus Dummy appears before them, still distraught after his confrontation with Stiyl. Here, the dummy has apparently used his Limen Magna to create makeshift limbs for the one that Stiyl sliced off. Both the dummy and Touma notice each other at the same time, with Touma shocked on how the dummy is doing to the bodies of the students—turning them into gold.

Seeing an incredibly enraged Touma, the dummy attacks him using the Limen Magna dart while using the molten gold for massive damage. Touma uses his right hand to block it, while trying to dodge the molten gold that the dummy is flinging about. However, the dummy is suddenly astonished at the fact that Touma has yet to turn into molten gold, and even destroys the dart the dummy is using. With this, Aureolus Dummy becomes incredibly ecstatic and becomes interested by Touma's right hand. He attacks again and again, and each time, Touma simply uses his right hand to block the dart which destroys it time and time again. Despite this, Touma's right hand continues to wear down, due to the injuries sustained from the contact with the dart.

However, the dummy attacks again, although this time, it seemed to target Aisa. Touma tries to stop it but it is too late, as the girl that was being carried by Aisa blocked the dart and saved her, turning into molten gold immediately after. Completely enraged, Touma grabs the chain that was connected to the dart and tries to pull the dummy towards him, forcing him to let go of it, injuring himself in the process as he steps on the molten gold he created. Unable to gather himself in time, Touma tactically launches himself on a window platform, surprising the dummy. Touma then jumps above him and tries to corner him. Unable to counterattack, already injured, and fearful of Touma's power, the dummy retreats before Touma could launch an attack.

Injured and wallowing in its own insanity, the dummy wanders the halls of Misawa Cram School, talking to himself and formulating plans for his next move. However, an enraged Touma continues his pursuit of him. He dashes towards the dummy, to which he tries to use his dart to attack him, however, Touma easily dodges his attack. Aureolus dummy attacks again, however, Touma counters with a punch of his right hand, destroying the dart and chain again, predicting his attack from the very beginning.

With Touma being able to get close enough to the dummy, he successfully connects to attacks—a punch to the face and a headbutt to the jaw. Wriggling in pain, the dummy reels back and tries to use his dart on Touma again. Seeing this, Touma manages to catch the chain with his left hand as so not to destroy it. The dummy immediately releases the chain afterwards, and tries to get away from Touma, however, his prothesis has been destroyed in the squabble, making him lame. With the dummy down, Touma uses the chain the dummy cut to strangle him.

In Touma's state of bloodthirst, the dummy pleads to Touma to spare him. Hearing this, Touma acquiesced and the dummy escapes with an inch of his.

End of the Aureolus Dummy
Managing to get away, a seriously injured Aureolus dummy tries to gather his thoughts. Here, he realizes that he is slowly dying and ebbing away after Touma hit him with his right hand. However, in this state of dying, he has realized something: he has discovered the answer to the question of whether or not a human can ascend higher without losing his humanity.

Immediately after, Stiyl arrives and finds him. Here, he asks Stiyl if he still wants to kill him even though he is going to die anyway, to which he responds that he has no interest in killing you. Stiyl then interrogates him about the dead Roman Catholic Knight a while back, to which he states that the dummy says he did not kill any of them.

Stiyl later clarifies to the questioning dummy that he has arrived not to kill him but to give his final blessings as a priest. Hearing this, the dummy could only give a genuine smile, as he finally gotten the answer he was looking for. Seeing that the dummy is within his limit, Stiyl calls out with magic name, to which the dummy tries to remember his own magic name, Honos 628, his name and purpose.

Stiyl asks if the dummy would like a final prayer for hims as a priest, to which the dummy declines. With that reply, Stiyl burns his body, incinerating him.

End of the first assault
Stiyl after performing his final services to the dummy as a priest, is still looking for Aureolus in the building. Here, he is somewhat anxious regarding Touma, whom he feels felt that he betrayed him. During the course of his search, he meets no enemies, apparently having Touma as bait working for him. This peace is later broken by a mysterious figure arriving before him.

Meanwhile, having defeated Aureolus Izzard and not being able to save the students that have been killed by, a depressed Touma urges Aisa to go home. Here, Touma becomes anxious of finally leaving the battlefield.

However, Aisa states that the Aureolus he fought was a fake, and explains to Touma how the real Aureolus would act and say he would leave Touma alone if he left. Touma, however, tries to confirm to Aisa if she intends to leave with him. She confirms Touma's suspicions, and explains that she has her own aims with partnering with Aureolus. Aisa explains to Touma, what she does for Aureolus, and why she goes to the outside despite having the power to attract and kill vampires. Aisa explains that vampires are exactly like normal humans, and her powers kill them without exception. Aisa continues to explain that she came to Academy City, the city of science, in order for her to gain the knowledge to remove her powers. As so she doesn't need to kill anymore, that's is why she became partners with Aureolus.

Aisa then asks why he is here with her, even when if she intended to escape, to which Touma replies that she wanted to save her. Aisa continues by saying that Aureolus wanted to save someone but he needed her powers' help to attract vampires. This gives Aisa a chance to use her powers not for killing but for saving.

Touma complains about this, stating that if she really thought that Aureolus was not a monster then he can't let Aureolus do his wrongdoings, in order for him to not to reach the point of no return.

Meeting the true Aureolus Izzard
Touma's worries are later realized, as the true Aureolus Izzard appears before him. Which surprises Touma, believing that he already defeated Aureolus a while ago, although he feels that he is not the same person before. Knowing why Touma is surprised, Aureolus states that he has no obligation of answering him, and has apparently come to reclaim Aisa back.

Angered, Touma tries to attack. However, with one command from his lips, Touma misses his attack despite the close range, with Aureolus apparently not being in the spot where Touma was sure he was in, and has moved. Touma tries to attack again, but the result remains the same regardless.

Bored of Touma already, Aureolus tries another apparently fatal command on him, but is stopped by Aisa. Touma pleads Aisa to get out of the way, but recalls on her power as Deep Blood. Seeing this, Aureolus is unimpressed with Touma relying on Deep Blood and compares Touma to himself, asking Touma the difference between them. However, Aisa interrupts Aureolus, saying that does not know the significance of Deep Blood, and has only come here to save someone he just met. Aisa then asks what Aureolus' objective is. Aisa states that if he is willing to get ordinary people who are not involved in this, get killed for some ridiculous reason, she will kill herself.

Aureolus relents to Aisa's words, knowing that they are just simply wasting time. He then commands Touma to forget everything that has happened here.

Index's involvement
Index, becoming suspicious of Touma's absence and excuses, sets forth to try and find him. Her suspicions are confirmed after seeing Stiyl's Rune cards applied outside Touma's room, and later follows the mana trail that Stiyl left as so he could maintain the runes.

Index's search eventually leads her into the belly of the beast herself—Misawa Cram School. Here, she notices the apparent strange effects of being inside Aureolus' barrier. Here, she sees the corpse of one of the 13 Knights of the Roman Catholic Church, and notes the strength of the one who created the barrier and the one who killed the knight.

She is later confronted by the still-living dummy that was now beyond recognition due to its injuries. Immediately after, the dummy is finally crushed and killed by none other than its creator, the true Aureolus Izzard. Here, he greets Index, apparently knowing her and her memory loss. He puts her to sleep and later takes her to the principal's office in the north building.

Second Assault
Touma returns outside of Misawa Cram School, and is aware of his memory loss (from Aureolus), although he is unable to reason why. Trying to find a hospital to treat it, Touma manages to dispel the effects of the memory erasure and rushes back towards Misawa Cram School.

Gregorian Chant Bombardment
Managing back, Touma realizes that the remaining Knights of the Roman Catholic Church have the building the surrounded. Here, Touma meets one of them named Vittorio Cassera, who informs him that they will be using the true Gregorian Chant to bombard the building. Touma pleads to Vittorio that there are still innocent people in the building, however, he states that their s are necessary in order for them to stop Aureolus. Despite this, the knight orders for them to carry on with the spell.

Immediately after the chant, the sky is torn asunder as a beam of light descends from the heavens and obliterates one of the buildings, setting up a chain reaction which causes the collapse of the other buildings. Touma tries to find survivors from the wreckage, however, he stops in his tracks after seeing that the debris and the building has stopped in midair. Here, all of a sudden, the building slowly starts to move by itself and back together, as if wasn't affected by the Gregorian Chant at all, demonstrating Aureolus' powers true extent.

Return to the battlefield
Having the chance to go back inside, Touma realizes that everything seems to have returned to normal, even the students that have been killed by the dummy's Limen Magna is still seemingly alive.

As Touma wanders around this queer spectacle, he comes upon Stiyl, apparently bereaved of his memories as well. Knowing how to remove the effects of memory loss on Stiyl, Touma is still hesitant however, as he might accidentally negate Aureolus reviving him from the Gregorian Chant bombardment. After confirming that Stiyl was in the building that was left intact by the bombardment, Touma finally dispelled Stiyl's memory loss as well as pay him back for using him as a bait.

While going to the unaffected North block of the Misawa Cram School where Aureolus' office would most likely be, Touma notes to Stiyl on how Aureolus Izzard was able to stop the Gregorian Chant, to which Stiyl is unbelieving of this as he believes that Ars Magna cannot be attained by human means. They argue on how Aureolus could've just used Ars Magna to conjure up vampires and just outright kill them if he really had Ars Magna, instead of going to such ridiculous lengths. Touma also notes how Index has become involved, Stiyl realizes what Touma means and states that Aureolus was Index's partner three years prior and intended to save her from the effects of the 103,000 grimoires in her head, however, since he hid himself for three years he has yet to learn that Index was already saved by Touma.

Confrontation with Aureolus Izzard
Stiyl and Touma confront Aureolus in his office, confirming their suspicion that Index truly was abducted by Aureolus. Here, Aureolus reveals to them that his plans, that he plans to summon a vampire in order to either implant their ability of infinite memory into Index or at least turn Index into a vampire. However, Stiyl sternly warns him that regardless of any method, Aureolus will never save Index, although he remains resolute in his vindication, because of this, Stiyl reveals to Aureolus that the person beside him—Kamijou Touma, holder of the Imagine Breaker—has already saved Index and is now living happily with her. Naturally, Aureolus didn't take this news kindly, and after seeing Index call out to Touma's name, finally loses his foundations of his beliefs and tries to kill Index but is unable to. In his enraged state he commands both Touma and Stiyl with his Ars Magna to the ground. Wanting to make them suffer more, Aureolus tries to prepare another attack, however, he is stopped by Himegami Aisa.

However, despite Aisa's urging, Aureolus now sees her as worthless and commands her to die. Immediately after, Touma breaks himself free from Aureolus' bonds and manages to dispel Aisa's after touching her, surprising Aureolus as to what Touma's power really is. Fed up with Aureolus, Touma lays down Aisa to rest and begins his confrontation with Aureolus, determined to break his illusions.

Kamijou Touma vs. Aureolus Izzard
During their confrontation, Touma negates every attack Aureolus uses on Touma using his Ars Magna, with Touma noticing that Aureolus uses verbal commands in order to attack. However, Aureolus sees one of the weaknesses of Imagine Breaker, seeing that Touma needs the power of touch with his right hand in order for him to negate his attacks. He summons a gun into his hand that can fire a bullet fast enough that the human eye cannot perceive, thus Touma is unable to touch it with his Imagine Breaker. Seeing that Touma could not possibly track the bullets fired from the gun, Aureolus summons several more pistols into his hand. Here, Touma is hit with several bullets but is not fatally injured, but is told by Aurelous that he will not kill him easily.

Stiyl tries to distract Aureolus regarding his Ars Magna as so Touma can find a way to counterattack. However, it is revealed by Index that his Ars Magna was achieved using a modified Gregorian Chant by the students of the cram school, in order to substitute the century long enchantment into only a few days order to achieve Ars Magna. Here, it is also revealed that Aureolus also revives the dead and injured esper students who overloads after using magic several times in order to facilitate his substitution. Enraged at this realization, Touma charges once again at Aureolus, throwing his phone at him as a distraction. At the same time as this, Stiyl makes up a bluff regarding Innocentius as well in order to distract Aureolus. Fed up with him, Aureolus commands Stiyl to float up and then made him explode violently, keeping Stiyl alive just barely, although distorted his body to look like a piece of artwork. This action though, causes several of the rune cards Stiyl keeps within to fall and scatter towards the ground. Meanwhile, Index immediately faints after seeing what happened to Stiyl.

Although terrified, Touma recalls Stiyl last piece of advice before being violently exploding, which is regarding the needles that Aureolus use during their battle to stab himself. Touma realizes that Aureolus simply uses the needles in order for him to concentrate. Here, Touma realizes that Aureolus Izzard does not change reality through his through his words, but through his thoughts. At the same time as Touma realizes this, Aureolus manages to summon a blade, knowing that Touma's Imagine Breaker lies within his righ hand, he severs Touma's entire arm from him.

Enter the dragon
Touma survives having his arm cut off, and begins laughing maniacally for some reason, apparently sure that he is going to defeat Aureolus, making Aureolus uneasy. Aureolus tries to attack but it does no effect on him, even after several barrages, Touma is still unscathed from his attacks, continuing his pursuit of Aureolus with nothing but a smile on his face.

Slowly but surely, Aureolus loses his confidence in his abilities, and becomes fearful of Touma. Despite this, he still tries to desperately try and kill him, but to no avail. Eventually, Aureolus could no longer keep his concentration, and now believes he cannot defeat Touma, affecting his powers considerably. Losing his needles, the things he needed to concentrate on his Ars Magna, Aureolus could only cower as Touma comes closer.

Finally, Touma speaks to him, demeaning Aureolus' thoughts regarding him thinking that cutting of his right arm would get rid of his Imagine Breaker. Out of fear, his doubts begins to affect his powers. Stiyl's gruesome demise is unraveled before his very eyes, with Stiyl returning back to normal, unharmed. At the same time as this, the space where Touma's arm used to be is replaced by the presence of a dragon. Thinking it was the result of his own anxiety affecting his powers, Aureolus tries to resist. However, he is left helpless, as the blood-dyed dragon that appeared forth before him opens its maw and consumes him.

Aftermath
Touma is sent once again to a certain hospital has his arm restored by Heaven Canceller, apparently surprised that Touma's arm was reattached neatly back to his body. Stiyl later visits Touma after Heaven Canceller, reporting current events and clarifying what had happened. Here, Touma revels at his performance in managing to Aureolus to self-destruct after having his arm cut. He is later told by Stiyl that he assisted during that time when Touma got his arm got cut-off, using the runes that were scattered after getting himself ripped apart to create an optical illusion as so that Aureolus would miss.

Stiyl continues to report that Touma did not kill the alchemist, and that Aureolus imagined the dragon arm in his darkest hour, and the fact that he was swallowed by the dragon, merely broke Aureolus' mentality, making him lose his memory. Stiyl states that the only real casualty of their mission (not including the Aureolus dummy) was the knight they saw when they entered school. According to Stiyl, since Aureolus lost his memory and Stiyl changed his appearance, technically rendering the man known as "Aureolus Izzard" dead. Hearing this, Touma is relieved and grateful for what Stiyl has done.

Index later visits Touma while he has a moment with Stiyl, which leads to a slight misunderstanding and argument with Index. Stiyl tries leaves shortly, satisfied with his place as Index's unsung protector, but not before being thanked by Index for being with Touma during the entire ordeal. After Stiyl left, Touma contemplates the uniqueness and importance of his Imagine Breaker, but is interrupted by Index. Here, Index clarifies to Touma if he has been fighting for Aisa's sake this time, and then states to Touma on how the Church is now keeping her.

Effects and future implications
Aisa would later start living with Kamijou Touma and Index for a short time before moving Tsukuyomi Komoe, who would later help her into her very own dormitory. Furthermore, the Walking Church that Aureolus promised to Aisa as his payment for her cooperation in luring vampires, was later provided by the Anglican Church after being taken in by them. As a result of the events in this arc, Misawa Cram School closes down, which forces Aisa to find another school. With the help of Komoe, she is able to transfer to A Certain High School much later.

In the world stage, the Roman Catholic Church is severely weakened after the 3,333 monks' Gregorian Chant was defeated by Aureolus during the use of their knights in this arc, the church is no longer able to perform one of their most powerful spells. Due to this, a power struggle takes affect in the Roman Catholic Church, this will later have lasting effects, as this event cornered the Roman Catholic Church, it would later influence their actions against Academy City in later volumes.

Finally, as for the dragon itself, perhaps the most hotly speculated and debated upon subject in the story of Toaru Majutsu no Index, is foreshadowed in this story arc to not to be just a mere illusion concocted by Aureolus. For much of the story, the true nature of the dragon is only hinted at, with an "invisible thing" making itself known after Fiamma of the Right severs Touma's right arm, as well as it and Touma's hand being crushed by Othinus in Baggage City. It would not be until the release of Chapter 67 of the Toaru Kagaku no Railgun manga that proves that Aureolus' vision wasn't just an illusion but in actuality. Furthermore, the mystery of the dragon only deepens as the chapter shows that there is more than one dragon residing in Touma's right arm.

Trivia

 * This arc does not appear in the manga version, and Aisa is introduced instead during the Kazakiri Hyouka Arc, where she enters A Certain High School as a transfer student and warns Touma about Kazakiri Hyouka. Stiyl Magnus is also later reintroduced to Touma much later during the Orsola Aquinas Rescue Arc.
 * According to Touma this arc occurs two weeks after he lost his memories which was July 28, this makes the date of this arc occur on 8 the 8th of August. In the Toaru Kagaku Railgun anime, Aisa is shown to have already acquired the cross necklace from Necessarius, which would imply that this arc has already passed. However, it is later revealed that the final date of the Poltergeist Arc is August 9, a day before the beginning of Sisters Arc in the Toaru Kagaku no Railgun manga timeline. We can infer that the there are timeline discrepancies in the Toaru Kagaku no Railgun anime adaptation.
 * The frog faced doctor points out in both the anime and the novels that in 10 days this has been Touma's second hospitalization, with that is possible to locate this arc in either the day 6 or 7 of August or perhaps even slightly earlier, that would mean that this arc does not conflicting with the others introduced in the Railgun anime.

Notable differences in the anime adaptation
Despite the anime adaptation's efforts to keep true with the novels, there are still several glaring liberties taken by the adaptation. One of the most egregious examples is the Deep Blood arc, taking away a considerable amount of content from the novels for the adaptation. Below is a list of notable examples:



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