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Exterior (外装代脳エクステリア Gaisō Dai Nō (Ekusuteria)?, lit. "Exterior Substitute Brain") is the 12th episode of Toaru Kagaku no Railgun T. It was broadcast on April 17th 2020.[1] The episode was directed by Mori Yoshihiro, the screenplay written by Uchida Hiroki, and storyboarded by Tachibana Hideki and Yanagisawa Tetsuya.

Kamijou's right hand was revealed to only have a temporary effect on Mikoto, who has transformed into a grotesque appearance. On the contrary, it caused Mikoto's form to change once again, her power growing as well. Those powers that continue to flow within Mikoto cannot be held back, but Kamijou and the others do everything they could to keep her at bay. Meanwhile, Kuroko confronted the puppet controlled by Kouzaku's ability. During this time, Uiharu and Saten successfully pinpointed the building where Kouzaku was actually located. Driven to a corner, Kouzaku lures Kuroko into her trap.

Gensei searches around Shokuhou's safehouse as he aims for the limiter release code for the Exterior. Shokuhou had set up several traps beforehand, hoping that it could hamper his movement, but Gensei paved his way through using the many esper abilities in his arsenal as a Multi-Skill. At the very last moment, Shokuhou uses a certain device and emerges with one final gamble!


With the help of the opening created by Gunha's Super Amazing Punch, Touma was able to move close enough to touch Mikoto. However, he quickly discovers that he cannot fully negate Mikoto's powers, and suggests that he and Gunha can only restrain her movements until someone else can discover and shut off the source of her power. Soon, Mikoto undergoes another transformation, and catches Gunha off-guard, causing him to bleed for the first time.

Misaki continues to follow Kihara Gensei as he wanders around her safehouse. She is certain that Gensei wanted her alive, and speculates that he needs the Exterior's limiter release code to gain full control of Mikoto's current form. Although Misaki is aware of the ability of Exterior to conceal itself to outsiders, she prepares to use her control of the facility as a countermeasure against Gensei. Misaki entraps Gensei inside parts of the hallway and fills it with sleeping gas, high voltages of electricity or bursts of flame. But, to Misaki's shock, Gensei safely escapes her traps with the use of the abilities of espers he "borrowed".

Soon, Misaki enters a conversation with Gensei about attempts to create a Level 6 esper. Gensei confirms that only the first-rank Level 5 can become a stable Level 6, and the current attempt on Misaka Mikoto is undergone by force. Gensei speculates that her personality would change into something "of another dimension" as soon as it reaches 53% of its theoretical limit, and a limiter release code is needed to stabilize her presence. At 100% of the theoretical limit—at the moment she becomes a Level 6—Mikoto's mind and body will be destroyed. Gensei is certain that, despite the instability of Mikoto as a Level 6, the territory of God can be witnessed at that very short moment, after which Mikoto may collapse into a state similar to a white dwarf, or open a gate to a new world like a supernova. Whichever case, Gensei knows that Academy City will be fully destroyed.

Gensei manages to track down Misaki's location with the use of his clairvoyant left eye and prepares to weaken Misaki's immunity to mind control by exposing her to physical torture. However, Misaki manages to escape as Gensei becomes excited at the intervention of Kamijou Touma and Sogiita Gunha against the rampaging Misaka Mikoto. Misaki admits that she cannot do anything against Gensei's Multi-Skill and Mikoto's continuing rampage, but soon finds something inside her safehouse that may be of use: graviton panels.

Meanwhile, Kuroko fights against Kouzaku Mitori's liquid metal puppet. With the help of the information they obtained from the Bank's records earlier, Kuroko prepares strategies to shut down the puppet's sense of sight and hearing and uses the opportunity to escape. Soon, Saten and Uiharu report to Kuroko that they have discovered Mitori's last known location on a specific office building. On Kuroko's request, Uiharu hacked all the cameras around the building, hopefully forcing Mitori's puppet to search and destroy the cameras in the area. But, to Kuroko's surprise, the liquid metal puppet continues to target her, and was even able to injure her right arm even as she attempts to confuse the puppet's echolocation. Kuroko is sure that Mitori herself is nearby, watching the fight unfold, and prepares to lure Mitori into a corner. However, she has a bad feeling that she is overlooking something important.

Inside Misaki's safehouse, Gensei is surprised to see Misaki again. Misaki offers to trade the limiter release code for the Exterior with her freedom, claiming that she does not care about Mikoto and she wants to escape before the rampaging Level 5 could destroy Academy City. However, Misaki actually prepares traps for Gensei; the first was Hag's Hug, a special panel that releases a destructive type of oscillation, and the second involves numerous graviton panels that only Misaki can control. Although Gensei saw through the Hag's Hug trap, Gensei manages to fall into a hidden pit covered by graviton panels. However, Gensei uses the Aero Shooter ability to escape from the pit and make a counterattack against Misaki.

Gensei once more falls into a graviton panel trap prepared by Misaki, this time designed to amputate his right hand. However, Gensei reveals that his body had undergone several prosthetic procedures due to his tendency to be exposed to danger, and he had already anticipated Misaki's plans to lure him into numerous traps inside the facility. Confident that Misaki has ran out of countermeasures against him, Gensei removes the air from Misaki's lungs, putting her into enough stress to render her vulnerable to her own ability. By using Mental Out against Misaki, Gensei finally obtains the limiter release code of the Exterior.

Adapted From

Major Events

  • Misaka Mikoto undergoes a second transformation after the failed attempt by Kamijou Touma in negating her powers. Touma joined Sogiita Gunha in keeping Mikoto at bay, hopeful that someone else can find and destroy the source of her rampaging powers.
  • Shokuhou Misaki stalked Kihara Gensei, who needed the limiter release code for the Exterior to gain full control of Mikoto's powers, as she prepared traps to deal with him. In the end, Gensei cornered Misaki and obtained the limiter release codes by using Mental Out against her.
  • With the help of Uiharu and Saten, Kuroko found Kouzaku Mitori's location and was planning to finally corner and apprehend her.


By order of appearance:


New Abilities


New Locations



  • When Kuroko remembers her investigation on Kouzaku Mitori's falsification of her Bank records while battling her Shadow Puppet, a scene from Railgun T Episode 9 is used as flashback, specifically where she and Uiharu investigate her records at the control center of the Bank.[4]
  • Kihara Gensei references Level Upper and its administrator Kiyama Harumi in this episode, and the second time they are referenced in Season 3.
  • Kuroko's special ointment created by Heaven Canceller, first seen on Tree Diagram Remnant Arc in Index II, is used once again by Kuroko in this episode, treating her arm wound caused by Mitori's Shadow Puppet.[5][6]

Cultural References

  • Garuda is a mythical bird, appearing in both Hindu and Buddhist mythologies, the mount of Vishnu.
  • A supernova is a powerful and luminous stellar explosion. This astronomical event occurs during the last evolutionary stage of massive stars.
  • A white dwarf is what stars like the Sun become after they have exhausted their nuclear fuel. Near the end of its nuclear burning stage, this type of star expels most of its outer material, creating a planetary nebula. Only the hot core of the star remains.[7]
  • The name of the countermeasure "Hag's Hug" might be a reference to the Old Hag or Night Hag, a creature from English folklore which would sit on a person's chest while they were sleeping, causing shortness of breath and paralysis.

Differences in Adaptation

This section requires expansion
Kuroko on Mitori's Bank info, Hound Dog reference
  • Unlike in the manga, Exterior's codes (including the boost code, the limiter release code and the self-destruct code) are merely referenced and not shown in any form.[8]

Animation Trivia

  • At least 1 minute of footage from the previous episode is reused in the beginning of the episode before actual original scenes for the episode are seen.[9]

Unanswered Questions

  • What methods did Kihara Gensei use to gather his subjects with special abilities for the use of Multi-Skill via Level Upper?
  • Did Gensei finally get the Exterior Limiter code from Misaki?


# Title Time Scene & Notes
Unverified Track
final phase Opening
Unverified Track Part 1
AIM Stalker Kuroko vs. Mitori, Part 1[10]
Unverified Track Part 2
nameless story Ending
Unverified Track Preview



This section requires expansion



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