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"Tree Diagram" (樹形図の設計者ツリーダイアグラム Shukeito no Sekkeisha (Tsurī Daiaguramu)?, lit. "Designer of the Tree Diagram") is the twelvth episode of the second season of the Toaru Kagaku no Railgun anime series, and the 36th episode of the series overall. It was first aired on June 28th, 2013. The script was written by Hanada Jukki, directed by Nihei Yuuichi, and storyboarded by Sonoda Masahiro. The animation was co-directed by Matsumoto Fumion, Fukuyo Takaaki, Hayashi Saitoku, and Furusawa Takafumi.

She had discovered that her enemy was Academy City itself. The Level 6 Shift Project, the "Experiment", held in the noisome depths of the "darkness" that Mikoto is obsessively fighting had struck her down with a sense of helplessness.

However, she herself must put an end to it. Finally, Mikoto sets forth towards a new target, the Tree Diagram, a supercomputer whom the best minds of Academy City seek out, and the very computer that suggested the plan in the first place.

Meanwhile, Touma once again meets Biribiri's little sister, hesitating before an abandoned cat, and is later involved in taking care of it.


In a recollection, a young Mikoto lives with her mother Misuzu . After reassuring Mikoto that her damaged Gekota plush toy will be "fixed by Santa in no time", Misuzu sends her daughter to bed. True enough, the next morning, Mikoto sees her favorite toy in good shape, and happily tells the news to her mother.

Mikoto has been used to seeing her mother fix things that she alone cannot. But how about now, where a very frightening nightmare became a reality? Ever since the reality that is the Level 6 Shift Project has been laid out to her, Mikoto's night have always been of uncertainty and insecurity.

Her friend Kuroko always gives her time to relax. But alas "reality is a harsh mistress".

Mikoto prepares to start her day and leaves ahead of Kuroko. Although she considers her certain task done, there's something else that she needs to end with her own hands.

Mikoto soon heads to a scenic spot in Academy City , where she seems to be waiting for something. As she glances to her phone which had the picture of her friends, Mikoto hopes that her friends wouldn't end up in trouble because of her. Then, as she looks at a blimp that shows the weather for the week, Mikoto remembers the term "Tree Diagram", Academy City's most powerful supercomputer, which is used to accurately predict the weather up to a month ahead. However, it is also used for many research projects in Academy City... of course, not excluding the Level 6 Shift Project.

Soon, the spiky-haired boy named Kamijou Touma accompanies Mikoto, calling her Biribiri, much to her chagrin, although Mikoto shows some uninterest in dealing with him. Touma takes the chance to ask Mikoto about her sister, and Mikoto is shocked at finding out that Touma met with her again. However, Mikoto is more focused in taking down the supercomputer that is responsible for giving the particulars for the Level 6 Shift Project, and soon leaves Touma behind, keeping her brimming rage inside her head.

Touma is left perplexed about Mikoto's behavior just a while ago, and soon finds himself with Mikoto's "younger sister", trying to feed some bread to a cat in a box, to no avail due to the nature of her ability. He soon discovers that she is unable to feed the cat due to the electromagnetic waves she emit, causing cats and other animals to feel unease when near her. Afterwards, Mikoto's "younger sister" urges Touma to take care of the cat in her behalf. Although Touma wasn't given enough time to explain himself, he decides to take the cat.

Later that afternoon, Mikoto's "younger sister", more specifically MISAKA #10031 , remembers reporting the experience of chest pains to her designated laboratory, causing Kanmi Eiga and Kusakabe Yumi , the two scientists in charge of her, to feel anxious about her upcoming experiment scheduled the day after. Although MISAKA #10031 assures that she is fine, her question about being given a chance to meet one's clone sends chills down Eiga's spine, while Yumi finds a clone of hers a useful thing to have, although she does not deny that such an encounter is creepy in itself.

MISAKA #10031 recalls about a memory of the Original shoving her away, and concludes that her existence was utterly unacceptable for her.

Mikoto soon heads to District 23, where she plans to shut down the nearby Information Processing Center, which acts as the terminal to the Tree Diagram.

Soon after getting off the bus to District 23, Mikoto quickly leaps into action, taking down every obstacle she can to reach the Information Processing Center. Mikoto's plan involves hacking into Tree Diagram and implanting a false prophecy that tells about the impossibility of developing a Level 6 in Accelerator , causing chaos not only in the facilities that work on the Level 6 Shift, but also in every single facility that depends on the infallibility of the supercomputer.

Back at District 7, Touma is accompanied by Mikoto's "younger sister", and he discovers that the cat is incessantly meowing. With the clone unable to read the cat's mood, Touma assumes that it is hungry and asks the clone to give it some food. Although reluctant to do so, the clone soon tries it out, and the cat receives the food she gave immediately. Touma then tells the clone that it is happy right now.

Soon, Touma tells the clone that she should name her cat, and the clone promptly gives unusual names to the cat, from "Dog" to "Tokugawa Ieyasu" to "Schrödinger", much to Touma's disappointment. The clone then decides to put the naming process on hold for the meantime.

The clone soon asks where Touma is going, remembering that it is a different route than the one leading to a certain vending machine. Touma explains that he is looking for a book at a nearby bookstore, and he is looking for an "old" book instead of the newer ones on sale. He adds that such a book is necessary, since his nun and shrine maiden friends has no idea about taking care of a cat. The clone seems disappointed that Touma is shifting the responsibility over the cat to his friends, but denies it despite Touma's suspicions that she is actually mad.

The two soon arrive at a branch of Book-On, and Touma heads inside while leaving the cat in her care. As she snows both nervousness and annoyance at how Touma has the guts to hurl a cat, the clone keeps the cat in her arms.

Nearby, Accelerator stumbles upon a group of thugs robbing a helpless boy in a dark alleyway. After swiftly taking care of one and frightening the other until he passes out, he sees a familiar sight of a clone in the other side of the street. Being reminded of his next experiment, he heads out to the sidewalk, only to be greeted by another clone, who reminds Accelerator that she is Clone #10031.

Upon seeing what looks like a harmless scene from the other side of the street, the clone who is with Touma a while ago, who is Clone #10032, heads out as well, leaving behind the cat with a slice of cake to eat.

In District 23, Mikoto finds it weird that most of the facility is not operational, from the lights to the cameras and elevators, and security is severely limited. She remained vigilant, although she still has a shaking feeling that how she is able to waltz in the facility is too absurd.

Soon, Mikoto heads to the main transmission room, which is empty and gathering dust, yet still functioning normally. She then finds out that there has been no data transmissions recently, something unusual for a supercomputer that should be accessed by facilities in a daily basis; upon further investigation, Mikoto discovers that there were requests, none of which being processed by Tree Diagram.

Then, as Mikoto stumbles upon reports dating July 8th, she discovers that the Tree Diagram suddenly disappeared from its orbital trajectory.

Subsequent reports reveal that the Tree Diagram has been destroyed.

Meanwhile, Touma is oblivious that there is no one waiting for him outside the bookstore as he continues his search for the perfect book for taking care of cats.

Major Events

  • Misaka 10031 and 10032 learn about experiencing the following emotions which are from then on permanently stored in the Radio Noise network: happiness, anger, frustration, irony, bewilderment, and sadness.
  • The 10031st Level 6 Shift experiment begins.
  • Mikoto discovers that Tree Diagram has already been destroyed.

Adapted From


New Characters


New locations


New Abilities

No new abilities were introduced during this episode.


  • Grow Slowly returns as the ending theme, replacing stand still from the previous episode.
  • Misaka 10032 identifies herself as such only after seeing both Misaka 10031 and Accelerator together for the experiment. Here, the Misaka 10031–10032 confusion is finally cleared during this episode as Misaka 10032 meets up with Misaka 10031, a fact that is only slightly shown in the manga and revelead in an omake of the 6th Toaru Kagaku no Railgun Manga Volume.
  • Touma references both Index and Himegami Aisa in her conversation with Misaka 10032 regarding taking care of cats, specifically Sphynx.
  • The Destruction of Tree Diagram and its Remnant is referenced during this episode.
  • The anime makes it clear that Mikoto was planning to stop the Level 6 Shift experiment by having Tree Diagram explain that the fight between her and Accelerator permanently prevented Accelerator from becoming a level 6 esper. She then planned to destroy Tree Diagram.


  • A photo of Mikoto and her friends that was taken from episode 20 of the previous season is shown in this episode.
  • Touma references his meeting with Misaka 10032 with the beverages last episode to Mikoto.
  • The cat that appears in this episode is the same cat that appeared back with Misaka 9982 in episode 05..
  • Misaka 10031 references Misaka Mikoto's rejection of her from the previous episode.
  • Misaka 10032 references animals' fright of Mikoto and her clones because of their electricity from episode 05.

Cultural References

  • Tokugawa Ieyasu is referenced by Misaka 10032 during this episode. He was the founder of the Tokugawa shogunate which ruled over Japan for more than 200 years.
  • Erwin Schrödinger is referenced as well by Misaka 10032, as a name for her cat. The reference here is different from episode 10 of Toaru Majutsu no Index as Touma simply states that it is taboo to name cats after him. Here, Touma references the entire thought experiment.

Differences in Adaptation

Animation Trivia

  • Animation from episodes 5 and 6 are reused as flashbacks for this episode. Moreover, as well as from the previous episode during Misaka 10031's recollection of Mikoto yelling at her.


# Title Time Scene & Notes
Unverified Track Opening
Unverified Track
Unverified Track Eyecatch
Unverified Track
Unverified Track Ending
Unverified Track Preview

Unanswered Questions

  • Who was the nun and shrine maiden Touma talks about to Misaka 10032?
  • Did Accelerator just save the person that was getting beat up by the thugs?
  • How was the Tree Diagram destroyed? and Why?
  • When Accelerator stated that there were dolls who could carry out their missions with silence, was he stating this out of a form of praise of the MISAKA clones?
  • Where was Mikoto's father in the flashback?
  • What will Academy City do now that it's "brains" have been destroyed?
  • What will Mikoto say to Kuroko when she goes back to the dormitory?
  • What exactly is the joint operation that Misaka 10032 is performing with Misaka 10031?


  • Mikoto: "Whenever I cried as a little girl, Mom would fix everything for me while I slept. If only that experiment and everything else that happened that day could also become just a bad dream... If only they'd never happened... But reality's a harsh mistress. I don't have my mom around to fix everything. And it's not like a miracle will happen, even if I begged for it. There aren't any heroes around to save me." —Mikoto's internal monologue on the reality of heroes.
  • Kuroko: "I will savor every moment of ecstasy until she drops the hammer!" — to Mikoto, as she cuddles Mikoto's side.
  • Mikoto: "I just hope they don't end up in trouble because we were friends..." —Mikoto regarding her friends before she becomes an enemy of Academy City.
  • Mikoto: "I hate that blimp. Because it means humans are acting in line with a machine's calculations." — to Touma, explaining how Tree Diagram affects people's lives in Academy City
  • Touma: "Spare me the disconcerting details!" — to Misaka #10031 as she tries to explain how Academy City handles stray animals (presumably through euthanasia)
  • Eiga: "What?! Just imagine there being a living, breathing copy of you, right in front of your very eyes! It'd even respond in 'your' voice too! I'm getting goosebumps just thinking about it!" — to Yumi, voicing her fright upon thinking of meeting a clone of herself
  • Misaka 10031: "My existence was not something Onee-sama could accept." — while remembering the Original's harsh words in her memories
  • Misaka 10032: ""Dog. This cat's name is 'Dog'," says Misaka, naming the cat. "It's a cat, but it's named Dog."
  • Touma: "Even as a thought experiment, any professor who'd even imagine putting a cat in a box that spews poison gas must hate cats!" — to Misaka 10032, referencing the Schrödinger's Cat though experiment.
  • Touma: "It doesn't like you because of your personal traits? Overcome that, and you'll find yourself with a true friend!"
  • Accelerator: "Not that one? Damn, you freaks keep confusin' the hell out of me." — to Misaka 10031, after mistaking Misaka 10032 on the other side of the street as Misaka 10031


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