Kuroko Shirai

"Judgment desu no!"

- Kuroko's Catchphrase

Shirai Kuroko is a level 4 esper and a student of Tokiwadai Middle School, as well as a member of Judgment. She can usually be found accompanying the third-ranked Level 5 esper Mikoto Misaka — her best friend, partner, and roommate. Though a minor character in Toaru Majutsu no Index, she gets a starring role alongside Mikoto in the Toaru Kagaku no Railgun sidestory.

Appearance
Kuroko is a girl with auburn hair tied into two curly pigtails; the rest of her hair is left to hang as two rows of fringes divided in the middle. Her pigtails are tied in place by a red bow each.

As per ruling of both Academy City and Judgment, she wears the uniform of Tokiwadai Middle School and the Judgment armband.

On her thighs, she secures a pair of black straps where she stores the metal spikes used to secure criminals.

Personality
Kuroko can be described as a "girl living in the future". She is used to the world 30 years from now portrayed by Academy City and is thus ignorant to the customs that present-day Japan still practice, like the "love umbrella", which students usually use to link their names to the name of their crush, and the conventional technology outside Academy City.

Aside from being a girl with a modernistic outlook, she can also be blunt when giving her opinions, and this has caused her to be at odds with Uiharu once. She is equally blunt and honest when it comes to her sexuality, oblivious (or rather, uncaring) of the discomfort that her aggressive expression of lesbianism causes in others, especially Mikoto, the target of her lust. Whenever she and Misaka are together (despite being in public) she will run up to embrace Misaka and indulging herself on Misaka's body, despite knowing she will get shocked as a result of her actions. Her tendencies to get intimate with Misaka are often expressed to almost ridiculous lengths; for example, when the two are forced to clean a pool, Kuroko tries to trick Misaka into drinking an aphrodisiac, of which she ultimately fails and drinks it herself by accident.

Her desire can be aroused by anyone who even resembles Mikoto, even her beautiful young mother Misaka Misuzu. It is for this reason that Mikoto tried her best to keep the existence of her "sisters" a permanent secret from Kuroko.

Although usually laid-back and friendly, Kuroko portrays determination and confidence in her own abilities when she encounters enemies, even to those whom she knows is more powerful than herself. To her credit, she is an honorable girl who keeps her word, is kind to children, and shares with Mikoto the same ironclad sense of justice that makes neither of them ever back down in the face of adversity. According to a particular rumor concerning her and Mikoto: "There's this horrifying teleporter in Judgment who'll tear apart your body and soul if she catches you...and there's another that rules over even that teleporter's body and soul - the strongest Electromaster," although Kuroko has no knowledge of this rumor herself.

Kuroko doesn't seem to like the idea of Gemstones, believing that such a phenomenon couldn't be possible without the Power Curriculum Program.

Abilities
Her ability is instant teleportation and she is called a Teleporter (空間移動 テレポート能力者 Kūkan Idō (Terepōto) Nōryokusha?, lit. "Space Manipulation User") because of this. Such an ability allows her to teleport herself and anything in her possession a certain distance in the blink of an eye. In volume 8 it is stated that her powers do have limits, being able to transport a total weight of 130.7 kilograms, to a distance of 81.5 meters from herself. It was revealed in Volume 3 of the Toaru Kagaku no Railgun Manga that before she went to Tokiwadai Middle School, she could teleport objects and other people, but not herself. She was eventually able to teleport herself sometime after enrolling in Tokiwadai. She is able to teleport objects inside designated targets, allowing her to "throw" the darts she carries on her thighs with perfect accuracy. One disadvantage of her power is that she has to concentrate on where she, the object(s), and/or person she holds will be teleported to, while working out the spacial co-ordinates of jumping between 3-dimensional and 11-dimensional space, so any disturbance in her concentration will render her powers useless, as demonstrated in her fight against Sherry Cromwell. Aside from her powers, Kuroko mainly relies on her Martial Arts abilities, which emphasizes throws and take-downs that compensate for her small size.

Other Appearances
Kuroko appears briefly in Ookami-san and her Seven Companions (also produced by JC Staff Animation Studios), smiling mischievously at the audience as a potential bride candidate for the boy millionaire Nezumi Chuutaro. This is, in combination with sharing the same animation studio, a result of Kuroko's voice actor rather blatantly using Kuroko's voice for the part of the series narrator.

Design evolution
There is little change in Kuroko's design. Haimura simply read her description and drew her without any real influence in her design. During her role as the primary heroine in volume 8, Kuroko's design was slightly modified to reflect her importance in the story; It is unclear what changes were exactly implemented. By volume 12, Kuroko becomes affected by deformed artstyle that Haimura has for the characters. Kuroko was designed with white ribbons for her winter uniform, but this is not brought up in the anime adaptation. According to Haimura, Kuroko was the easiest character to transfer in manga format, for her detailed design for the Toaru Kagaku no Railgun manga.

Trivia

 * In episode 15 of the Index anime adaption, during the Angel Fall arc, Shirai Kuroko is depicted to have apparently switched with the US President Barack Obama, using his catchphrase "Yes. We. Can". This was not in the Light Novels, and could be seen as a in-joke for the anime producers, considering Kuroko can also mean 'black child' literally in kanji and also because the episode was aired during U.S.A. presidential elections.
 * Satomi Arai, whose comedic yet thoughtfully mature performance as Kuroko won her the Best Supporting Actress trophy during the Annual Voice Actor Awards in 2010.
 * Although usually displayed and used as comedy relief, Kuroko displays a strong constitution, surviving constantly shocks from Misaka, having her neck dislocated by the Dorm Mother, repeatedly pounding her head on solid objects in fits of rage/terror/stupidity and having her joints pierced by Musujime, from which she recovers quickly.
 * There are hints throughout the Toaru Kagaku no Railgun anime which suggest that Kuroko is fairly adept with a camera, and may possess some degree of skill in photography.
 * Kuroko also has a collection of Misaka Mikoto's pictures that she keeps in an album named "Onee-sama's secret" as shown in Toaru Kagaku no Railgun anime episode 2.
 * Her ability is listed as No. 478 in the Bank.