"Everyone's 'Big Sister'" (みんなの『お姉さん』 Min'na no 'Onē-san'?) is the 14th chapter of Toaru Kagaku no Railgun Gaiden: Astral Buddy, released on September 27th 2018.


In the employee cafeteria, Professor Toomine examines Hokaze Junko's progress. She says that Junko's growth is not only unexpected but is also well-suited for the facility's esper powers development. She notes that her body strengthening ability is stronger than it was originally and has a high-level regeneration. A regeneration that is so quick that her wounds heal instantly. Toomine however points out that there is a price for this power--the rapid cell division and injury healing place a heavy burden on her mind and body. The pain that Junko experiences is the result of this, affecting the usage of her power. She notes that Junko has the potential of becoming a Level 5, but because of her subconscious defense instincts it prevents her from drawing out her full power. And the only way to achieve that is specialized care, as such she has requested expansion of her budget.

Toomine asks if the request will be approved, but her colleague says it is unlikely as the children of Ideal weren't gathered for powers development. Toomine can only sigh, saddened on how they are robbing the children's futures. She recalls that one little girl asking where "Misaki-chan" was, and is saddened by her own callous behavior, as she notes that they can't possibly tell them that the true Level 5 esper powers development is being given to only one girl: Shokuhou Misaki.

Meanwhile, Ayu is sitting by herself as the other girls play. She recalls the head researcher tell her the truth about the powers development of Ideal--that only of one of them can participate and they must choose which one as they don't have enough money, even though they all have the potential to advance. The man asks Ayu who they should as she is a big sister to the girls and should know better than anyone.

Back with Ayu, she falls into despair, having to make a difficult choice as she is the oldest, knowing that there is a wall in developing powers and not all of them can continue. She wonders what happens to those who can't participate. Then a couple of girls pile on top of her, wanting her to play with them and she acquiesces. Seeing them, Ayu is dismayed on how their hard work and effort goes unrewarded like it should be.

Back with professor Toomine, the girl who would one day become the Ghost Girl hugs her from behind, surprising her. The girl notices that Toomine isn't wearing any makeup, to which she replies that she didn't have enough time. However, she notices that the girl may have been interested in makeup. Toomine agrees but tells the girl not to tell the other girls. Toomine recalls that the girl was born with a weak body, as such she has spent most of her life in the hospital. She can't go to school or play with friends her age. She says that the girl has never once come out and asked to do something since she arrived. She believes that this is because she has either spent more time with doctors or because she knows her hope can never come true. Because of this she lets her do what she wants, if she could tell what that is.

Meanwhile, back with the other girls. Rakko is doing a similar test to that of Iruka. She's trying to move the hand of the sensor little by little, and succeeds, managing to get a small reading. Everybody cheers including Iruka her younger sister, happy that she has a power like hers. However, Rakko is not happy as it was insignificant and that she has no talent. Ayu arrives and tries to convince her otherwise, but slowly realizes her own sad fate and begins crying instead, leading to Rakko also crying.

Seeing the sad mood in the facility, Iruka stands and tells the girls to follow her, saying that she wants to show them something. As they sneak around, they come across a familiar young researcher girl and an older woman walking together in the hallway. Iruka gives the signal to one of the girl as the two researchers approach and uses her powers to divert people's perception. They also come across Junko and Iruka orders her to be captured, much to her protests. Rakko asks how much further they are going to go as they climb a flight of stairs towards a door leading to the roof. They open it and find themselves outside with a familiar building in the distance. Iruka says she found the roof while exploring the laboratory, and notes the great view and that it is her favorite place. Naturally, the girls are amazed.

Ayu assumes that Iruka used her powers to send an optical signal to unlock the scanners that lock the doors. This impresses Ayu, calling her a tomboy, though Iruka says that she doesn't go to where the researchers will get mad at her. Seeing all her friends together looking at the vast landscape of Academy City, Ayu smiles and thanks Iruka for all she has done. On the side, Rakko misunderstands Junko's caution, believing she hates her.

Ayu later confronts the head researcher, saying that she will be redrawing from the esper powers development. The researcher asks why, to which Ayu says that the smiles of her friends mean more to her than anything and that imagining their sad faces if she chooses any one of them. She says that if she joined the experiment with that feeling she doubts her powers will grown and further. With this, Ayu is determined with her choice, and the head researcher accepts her choice. Ayu believes that her decision is for the best.

Coming outside the office, she bumps to one of her friends, wondering where she went. Believing she made the right choice, she smiles and takes their hand to play, not knowing to the great regret she will experience later on as the experiment was introduced to them the following day.

Major EventsEdit

  • Flashback chapter
    • The true extent of Junko's powers are explored.
    • Mitsuari Ayu's past is explored.


By order of appearance:

New CharactersEdit


New AbilitiesEdit

  • Ability similar to Wave Conductor - Yumiya Rakko
  • Unnamed diverting people's perception esper ability - Unnamed girl



  • Junko is revealed to be a candidate for becoming a Level 5.
  • When Iruka and Ayu were trying to escape the facility to the roof, Kuriba Ryouko is seen briefly in a hallway alongside an older woman presumably her mother.


  • Toomine recalls one of the girls asking where Misaki. Moreover, scenes from the same chapter are reused as Ayu slowly breaks down as she comforts Rakko.[1]
  • Ayu's decision here would later impact her to the point of wanting revenge in Shinyaku Toaru Majutsu no Index Volume 11.

Unanswered QuestionsEdit

  • Why was the Ghost Girl born with a weak body and could not be cured?
  • Who was the woman Kuriba Ryouko was with?


  • Mitsuari Ayu: "Zero and one are entirely different. Taking care that very first step is significant progress. Now you just have to take more steps like that.☆ It might be slow, it might be gradual, it might not always work out, but if you... keep going without giving up... then surely... surely..."--to Yumiya Rakko.


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