Kusakabe Yumi

Kusakabe Yumi (草壁優美) is a character introduced in Toaru Kagaku no Railgun. She is a researcher who apparently supervises on the treatment and training of clones after they are "born". Like Amami Eika, she originally did not have a name in the original manga until her introduction in Toaru Kagaku no Railgun S.

Appearance
She has brown hair which she keeps in a ponytail, and two fringes which rests between by a black hairband. She wears a round spectacles, and has fierce eyes. She is taller than Eika.

Personality
Cold and calculative, she is a no non-sense superior to Eika, seeing the human clones as nothing more than necessary pieces in the experiment.

Sisters Arc

 * Main article:Sisters Arc

In a flashback to May of the current year of the Story Timeline, Yumi supervises the birth of Misaka 9982. and explains on how the clones are grown fast, how they learn through Testament, and why they don't need complex emotions to Eika.

She later talks to Misaka 9982 on how experiencing things on the outside world is different from learning it to Testament, and later talks to her about on how she maybe able to meet her Original, Misaka Mikoto. She may have been the one that had the clones refer to Mikoto as Onee-sama, after Misaka 9982 questions Yumi regarding her original. Before Misaka 9982's training starts, she orders to clean up a room where a recent experiment with the Sisters have been conducted, where all of them died.

She and Eika later reappear while Misaka 10031 gets a checkup during the fateful day that she is to fight Accelerator. Here, she notes that there is nothing wrong with Misaka 10031 other than a pain in her chest (relating to Mikoto yelling at Misaka 10031 after she discovers the experiments is still going on). After Misaka 10031's asks what they will do if they had a clone appear in front of her, Yumi agrees with Eika after she exaggerates her fears of getting a clone.

It is unknown what had happened to her or to Eika after the experiment's termination, though it can be assumed that they escaped any sort of justice or punishment.