Mental Out Arc

The Mental Out Arc is a story arc introduced in Shinyaku Toaru Majutsu no Index, encompassing the content of the 11th Shinyaku Toaru Majutsu no Index light novel volume. It primary deals with Shokuhou Misaki, the 5th-ranked Level 5, having to deal with a conspiracy against her that is connected to her past with Kamijou Touma.

Background
The conflict of the arc is rooted in the similarities between Shokuhou Misaki and Mitsuari Ayu, both having similar powers and both having similar memories with Touma. In accordance with Parameter List, Misaki was given focus and development for her powers while Mitsuari was kept as a mere back-up in the event of her death.

Mitsuari had already met Touma prior to him meeting Misaki. Due to the circumstances surrounding development, Mitsuari falls into despair and considered suicide. When she was about to go through with it, she sent a message to Touma, hoping that he would save her. However due to bumping into Shokuhou Misaki at an intersection, Touma lost his phone and as such was unable to reach her in time.

She survives her attempt at Ground Geo, however, and was then drawn to Academy City's dark side. She discovers Misaki's relationship with Touma and thus resents her for not only stealing her chance to become Level 5, but also for being saved when she wasn't. Shundou Toshizou would later make use of her, manipulating Mitsuari without her noticing, for the purpose of finally stealing Mental Out for himself. For this purpose, he likely lends her the equipment that she would use for her vengeance. Using the equipment, she camouflages Ground Geo using the _Over OS and somehow inserts a Strobila on Misaki in order to torment her and create doubt that would eventually lead to her to erase her own memories of Touma believing them to be fake.

Conspiracy against Shokuhou Misaki
Early in the arc, Misaki reminisces of her time with Touma in the summer a year ago before he lost his memories of her. She visits places around Academy City that is significant to her memories of Touma until at last she arrives at Ground Geo. There, she falls for Mitsuari's ruse and believes her memories have been manipulated.

Misaki later concludes that the only other person she knows that is capable of matching her is Kumokawa Seria and travels to where she believes Seria is hiding. When at last she comes upon the place is caught in her trap by her. Misaki pleads her case to Seria and tells her of its involvement with her memories of Touma. Convinced, Seria helps her and soon discovers that a Strobila device has been implanted into her. Misaki later leaves with the Strobila in Seria's possession in order to find out who the true culprit behind it being implanted into Misaki, pained by the thought that her memories with Touma might be false.

However, Seria is not the only one who is aware of Misaki's investigation. Misaki is visited again by the Ringlet curl girl asking her if she needs assistance, though Misaki dismisses her again. Much more pressing however is Mitsuari discovering that Misaki has finally discovered what was going on. After the removal of the Strobila, Mitsuari had several of her subordinates approach Misaki disguised as Emergency Aid workers to replace it under the guise of treatment for instability. But Misaki sees through their ruse and manages to take control of them. She questions one of them and discovers that the Strobila had no actual data and that it was only used to make her doubt her own memories so she would erase them herself.

She is enraptured by the revelation that her memories may be real after all. She then calls upon the Ringlet curl girl and the rest of her clique that is willing to follow her as she needs their aid in finding out the truth behind the doubt in her memories, which is in Ground Geo. Prior to the arriving there, she speaks to Seria over the phone regarding her plan. Seria warns that the culprit has the power and conviction to do something on the scale of breaking away from the loyalty of the Board of Directors, and that is just a step in their preparation, telling Misaki to be careful as Touma isn't strong enough to handle someone's death. Seria then says that if she does die, then she will give her the proper decorations so she should make sure to contact her.

Arriving at the Ground Geo, Misaki strikes the ground's surface with a screwdriver and proves her suspicions. The entire Ground Geo has magnetic dust cover it and through it has been made to look different from her memories using colored magnetic dust that acts as a monitor.

Shokuhou Misaki meets Mitsuari Ayu
Now knowing the truth, Mitsuari Ayu with the _Over (Out_Sider) arrives and disguises herself and the machine with the Designers' Gel to look like an obese Misaki. Seeing the huge mass in front of her in a Tokiwadai uniform, Misaki questioned if she was really in middle school, to which Mitsuari responded that she could ask the same. When Misaki attempted to use her ability on her, Mitsuari told her that it won't work and that she wouldn't have shown herself if she thought it would.

Mitsuari then began her attack, using the magnetic powder to make "illusions" and terrify Misaki. However, Misaki was not unprepared as she brought with her the volunteers of her clique to aid her. They destroy the dust with their powers. However, Mitsuari wondered where the other hidden pawns are, recalling that Misaki can only accurately control up to fourteen people at once and threatening to cut off her arms and legs, leaving just her brain that can't crawl. Slowly, Mitsuari marks the location of each clique member. Mitsuari asks to Misaki how many more there were, saying that she could crush them as long as she knew where they were and adding that Misaki couldn't stand to see one of her pawns die despite arrogantly controlling people. Seeing her reaction, Mitsuari wondered if the look on her face meant that she had ordered them all to withdraw, which saved her the trouble.

Wondering who her enemy was, being familiar with her past and powers and being able to outdo her in psychological warfare to such an extent, Misaki asked her if she had some connection to her, to which Mitsuari replied that she did as otherwise she'd have no reason to resent her and when Misaki said that she'd never met her, said that if she had met her, she wouldn't have been able to resist killing her then. On being told she was insane, Mitsuari laughed and asked who can prove that people like them who readily manipulated people's minds still had sounds minds of their own. As Misaki faced her, Mitsuari began to alter the surroundings again, but to her surprise Misaki started to throw her remotes at her face. As Mitsuari covered her face, Misaki got closer to her and grabbed at her neck, pulling out a Strobila embedded in it. Thinking that she'd removed Mitsuari's means of resistance, Misaki used her ability again and Mitsuari pretended to have fallen under her control.

Using her remote, Misaki interrogates her under the impression she is controlling her. Here, Mitsuari reveals that what she was doing was revenge and to punish her for stealing 'her'. Misaki asked her who she was and Mitsuari claimed, to her shock, that she was Shokuhou Misaki. Mitsuari's ruse pays off as she is able to catch Misaki. Mitsuari plays around with the magnetic dust to scare Misaki until at last she reveals herself to Misaki with the _Over (Out_Sider) beside her. Upon seeing her, Misaki feels that she is similar to her. Mitsuari confirms this, revealing that she had Mental Stinger and is stuck at Level 3 because of Shokuhou Misaki's powers being developed instead of hers.

After revealing herself she tells Misaki that her powers fail to affect her simply because they are similar allowing for her to interfere with its workings. Misaki then starts to deconstruct Mitsuari's reasoning on her grudge pointing out its flawed nature and using Touma as an example of his determination dispite being a Level 0. Mitsuari mocks her and reveals that not only does she know Touma but her real reason for seeking vengence is because she was not saved unlike Misaki and that it was her fault. Mitsuari manages to get close to Misaki and is able to use Mental Stinger on her giving Misaki a strange sensation. In spite of this, Misaki points out her action's futility as having the same type of power any interference can be deflected, but Mitsuari believes it, saying that it's true only if both reject it and then asks Misaki what will happen if she accepts it instead. Misaki then realizes Mitsuari is not directly using her power on her mind, but rather as an ignition to make her lose control of Mental Out to which Mitsuari confirm saying she is using Misaki's power to drag her in her head, which she succeeds in immedietly after.

After Misaki's consciousness is trapped in her mind, Mitsuari explains the details of her attempted suicide at the power station, where three days following his failure to save Mitsuari Touma meets Misaki about to erase her memories. Mitsuari explains further that the reason Touma was not able to save her was because of him losing his cellphone when they first met bumping into one another. After finishing her story Misaki asks her on the reason she is wearing the Designers' Gel suit, and Mitsuari realizing the true question answered that she did not want Touma to know that she was still alive, but had fallen to such a level. After hearing this Misaki then declares that she will save her because it is what Touma would do.

Mental Out vs. Mental Stinger
Trapped within Mitsuari's mind, Misaki tries to figure out Mitsuari's motive despite the fact that Mitsuari can read her every thought. In spite of her taunts, Misaki determines that Mitsuari's revenge is beyond just simply killing her. But it was too late, as Mitsuari Ayu herself is weakening the world that Misaki is trapped in as it is no longer needed. Much to Misaki's horror, the _Over Modelcase Mental Out appears before her. Mitsuari reveals to Misaki that it is not functioning as intended as it cannot replicate her powers and as such she will complete it by putting Misaki inside the machine, and then she will finally use her own Mental Out to destroy Misaki's memories with Kamijou Touma.

Though Misaki is trapped physically in the real world by the OS and mentally by Mitsuari's powers, she still has a trick up her sleeve. Using her clique to attack the people who provides the Five OVER Out Sider's viewpoints that allow it to create its illusions, and then hijack the lenses to provide malicious feedback to _Over Out Sider, allowing the clique to take control of it. Now with the OS in her control, Misaki uses it to attack Mitsuari. In turn, Mitsuari also uses the _Over Modelcase Mental Out to counter it. The battle turns into a physical confrontation between Misaki and Mitsuari, and though Misaki tried to use OS to create illusions against Mitsuari. However, Mitsuari manages to use her phone to filter out what she sees. In the end, Mitsuari manages to hit Misaki's head and used her smartphone to finally beat her, knocking her unconscious.

After coming to, Misaki finds herself inside the capsule of the _Over Mental Out, being submerged in conducting fluid, which paralyzes her, for the electrodes that Mitsuari is connecting to her body for the machine. Despite this, Misaki tells Mitsuari the non-believing that Touma will come to save her in spite of all odds, as he is her hero. Beyond all hope, Misaki blows upon the whistle Touma gave to her a year ago so that he will come to her. Angered by her, Mitsuari tries to strangle Misaki, rationalizing that though Touma may be a hero he isn't almighty and that she is an example of that limitation. However, beyond all hope, Mitsuari's expectations are overturned at last and Touma finally arrives as if to answer Misaki's call.

Mitsuari later breaks down at the sight of Touma's arrival, making her ability go haywire, though Touma easily negates it. Touma later helps resolve the conflict that happened there in the name of the memories that they had for him that summer a year ago. Misaki then tells Mitsuari to get saved by Touma as she has been saved enough.

Aftermath
After resolving the conflict with Misaki and Mitsuari, the former visits Touma in the hospital. She meets him again as he sits alone on a bench. As Touma cannot remember Misaki after they meet their meeting is a poignant one as Misaki once again introduces herself to Touma. Misaki asks Touma if he remembers Mitsuari Ayu from the day before, to which he does. He remarks why she would know that, to which Misaki references how he remembers the enemy but not the one he saved. Misaki tells Touma that the _Overs used in the battle were destroyed and that Mental Out ability has not been mass produced. Touma is unable to connect that Misaki is the one who has the Mental Out ability, though Misaki tells him to pay no mind to it. Misaki then tells Touma that Mitsuari has been “officially” sent to the Reformatory, though her eventual fate may be unknown due her reckless actions, and that they may need to watch over her to protect her from the darkness.

Misaki then sits next to Touma, asking him why he showed up in Ground Geo, to which he states that his “senpai” asked him to do so for the sake of a girl’s birthday. Touma then asks again who she is, to which Misaki says that he will forget anyway and that it would be hard for her to have the motivation to name herself. Misaki then kisses Touma in the forehead. This shocks Touma asking her what she is doing and Misaki tells Touma not to worry about it as he will forget it soon enough. Misaki then simply tells Touma that she is a girl he once saved. Before leaving, Misaki says that if Touma is able to remember her then she would like to have an important talk with him. Misaki leaves, still hoping for a tiny miracle that would allow Touma to remember her to happen.

The return of Aleister Crowley
After the defeat of Mitsuari Ayu, Kihara Noukan goes to Celestaquarium for his 72nd and final request from Aleister Crowley. He later kills Shundou Toshizou, the one who was manipulating Mitsuari and Deadlock in order to steal Mental Out from Shokuhou Misaki.

Noukan then begins communication with Aleister Crowley in the Windowless Building. Noukan asks if his work has satisfied him, to which Aleister says that it is only the beginning. Noukan asks if Aleister has found something to make up for what had happened to him by fighting the magic gods. Aleister replies that it was necessary even if he had gained nothing, to which Noukan says that he has a habit of sounding rational when he's actually handling everything through emotion. Aleister retorts by paraphrasing Noukan's own words that scientists must be romantics and they must always work to fill people with dreams. With a sigh, Noukan agrees as it is romance that separates men from beasts. Aleister asks if he is wrong, to which Noukan replies that he should ask the Heaven Canceller instead, his attending physician, but says if he has to give an answer as a Kihara, he says that what he is doing will definitely fall on the side of evil, a bland one at that. Noukan then says that since he has returned order to his rule as he has tasked him, he requests that he should use the power he has returned to him to destroy all the irregularities known as magic.