Shirai Kuroko

Shirai Kuroko (白井 黒子) 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 Misaka Mikoto — 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 affections. 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. She even tried to steal some of Mikoto's underwear and even became aroused by the smell of Mikoto's bed. It is for this reason that Mikoto tried her best to keep the existence of her "sisters" a permanent secret from Kuroko. Despite her overzealous attempts at gaining Mikoto's favor, her affections appear to be genuine; it has been shown on a few occasions that she is genuinely in love with Mikoto, even allowing herself to get severely hurt (see Tree Diagram Remnant Arc; Volume 8 Index Novel) in order to help Mikoto. She is regarded as Mikoto's best friend. However, when her memory of Mikoto was wiped by Shokuhou Misaki, she claims that she "doesn't swing that way" when Mikoto becomes affectionate, indicating that she may not be a lesbian at all, and that she is confusing her strong feelings for Mikoto as love, or that her sexuality is exclusive to Mikoto and not to the female sex in general.

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 had no knowledge of this rumor until a robber she took down told her about it.

Kuroko can be close-minded at times refusing to believe in urban legends without any concrete evidence and even then it will still take some time for Kuroko to accept it. Examples include the boy with the power to make other powers stop working, despite knowing him personally and it was not until when she saw the effects of the Level Upper that she began to suspect it and even than it was only after seeing it a considerable amount of times. Kuroko doesn't seem to like the idea of Gemstones, believing that such a phenomenon couldn't be possible without the Power Curriculum Program.

Background
Kuroko is a first grader from Tokiwadai Middle School. A year before she entered the prestigious school, Kuroko joined, a special public committee group whose duty is to maintain peace and order in Academy City. The first major case she handled (along with Uiharu Kazari and Konori Mii) was the arrest of a bank robber who can use the esper ability Equal Speed. Despite her young age, she stood up to the much older esper and was beaten up in the process, although a particular bolt of lightning saved her from imminent danger.

She is in love with Mikoto, whom she calls "Onee-sama" (big sister); she is on the constant lookout for a chance to get physically intimate with Misaka (getting called a pervert and electroshocked in the process), and tends to get jealous if someone else gets her attention; this unfortunately happens to Touma.

Level Upper Arc

 * Main article: Level Upper Arc

Kuroko is seen doing her duty as a member of Judgement detaining espers whose powers were enhanced by Level Upper. Due to injuries she sustained from fighting Level Upper users, she couldn't partake in rescuing Uiharu from Kiyama Harumi or help Mikoto fight the AIM Burst.

Big Spider Arc

 * Main article: Big Spider Arc

Kuroko aids Mikoto, Konori Mii, and Kurozuma Wataru in fighting and putting an end to the Skill-Out gang, Big Spider.

Poltergeist Arc

 * Main article: Poltergeist Arc

Kuroko is first seen in this arc with Mikoto and Ruiko helping Uiharu's new roomate move in. Later they go to a festival where a Poltergeist happens, and after observing Erii's odd behavior right before the incident and some investigation, she begins to suspect that Erii is the one responsible, which strains her relationship with Uiharu. When the head of MAR, Therestina Kihara Lifeline's true intention for Erii and Kiyama's students was discovered, she slapped Uiharu to snap her out of her emotional breakdown. Later, she and Mitsuko joined forces to stall the MAR powered suits, then came to Mikoto's aid against Therestina herself. At the lab, they are again confronted by Therestina, only this time she Capacity Down to disable them, except for Saten as she was a level zero and thus uneffected by capacity down, and went ahead to disable it, an act that earned her Kuroko's respect.

Sisters Arc

 * Main article: Sisters Arc

Although showing rarely, she is the one who opens up the question to Mikoto on what would happen if she were to meet a clone of hers, to which Mikoto gives an answer that she will soon regreat. Throughout the story arc, she becomes concerned as to what Mikoto is holding and laments on how Mikoto cannot trust her enough to tell. Kuroko is forced to lie to and deceive their dorm manager for Mikoto's sake as she begins her one-man mission to take down the Level 6 Shift Project.

Later, after Mikoto believes she has shut down the Level 6 Shift Project for good, Kuroko calls Kazari and Ruiko to determine what they should do with the current situation with Mikoto. Ruiko concludes that since Mikoto goes out every night and comes home tired, it can only mean that there is a boy involved, much to Kuroko's disbelief. After an alarm goes off in Vending Machine 7116, she immediately concludes it is Mikoto and proceeds to go investigate alone. She later finds Mikoto with Kamijou Touma leading to the now classic scene of their meeting. Regardless of her horror of Mikoto meeting with Touma, she is relieved that she has returned to her old self.

This is however shortlived, as Mikoto later discovers that the Level 6 Shift Project persists. Kuroko sees through Mikoto's change of behavior and suspects that Touma might have something to do with it, but is then asked by Mikoto a hypothetical question on what Kuroko would do if Mikoto were to do something irreversible to Academy City, to which Kuroko says that she will do her duty even if it is her Onee-sama. Kuroko's words relieves Mikoto but it doesn't help Kuroko's worry. Finally, as Mikoto goes off to destroy Tree Diagram to stop the aforementioned project, Kuroko lies alone in Mikoto's bed worrying about her. She recalls on how Mikoto acts normally when referencing "that idiot" (Touma), and wishes for him to come and do something. Her wish is seemingly granted, leading to their second meeting in the Sisters Arc.

As the Level 6 Shift Project is ended by Touma and the Sisters, Kuroko tracks down Mikoto on a bridge, whom has just met Touma but is unable to give the cookies she baked for him. Kuroko is surprised by Mikoto's reaction after she hears Touma say her name for the first time, saying that it is an expression she has never seen on her before.

Silent Party Arc

 * Main article:Silent Party Arc

Kuroko plays a supporting role in the arc. As Mikoto returns back to normal after the events of the Sisters Arc, Kuroko welcomes her back with open arms. When Mikoto once again starts acting secretive, Kuroko is fine with it, believing that Mikoto will be back, and supporting in her endeavors. However, when she opens up to them that she needs their aid in helping Febrie from the dark side of Academy City, Kuroko jumps at the call to help her. She is the one who rescues Mikoto from the office building STUDY stuck her in after she was captured, using Kazari as the one who tracks the nanodevice embedded inside Mikoto, and Ruiko as the lookout. She easily defeats the security robots stationed there. Kuroko gets involved when the group decides to take on STUDY and the Silent Party without any help at all from Anti-Skill for the sake of Febrie and Janie, Febrie's sister. She stands as a sole guardian of one of the Academy City Research Exhibition Assembly venue entrances, and faces off against several of the 20,000 plus STUDY Powered Suits controlled by Diffusion Ghost. After being joined by other Judgment members rallied by Yanagisako Aomi, she is shocked after all of them copy her famous catchphrase. She then does battle against the Powered Suits, and uses the javelins from Tokiwadai, easily defeating a Powered Suit with a single hit. She also uses her ability to rescue Judgment members who are in trouble.

Kuroko is part of the little conference held after Mikoto defeats Aritomi Haruki, STUDY's leader, who has launched the AIM bomb. Here, she is the one who is to go with Mikoto and teleport her back after she has used the Ekaterina II S to destrou the AIM bomb. As they strap themselves in the mecha while waiting for launch, Mikoto apologizes to Kuroko for involving her, to which she replies that she doesn't mind for she is finally fighting side by side with Mikoto. With that, they are launched into space by Mitsuko's Aero Hand. Kuroko becomes visibly sicked upon arriving in the upper atmosphere, but manages to teleport away as Mikoto begins to do her part. Kuroko teleports an exhausted Mikoto back to earth after she destroyed the AIM bomb. She is later seen asleep near Mikoto along with Kazari, Ruiko, Mitsuko, Kinuho, and Maaya in the grounds of the Academic Assembly venue, most likely tired, as the Assembly begins in earnest.

As Janie and Febrie are in a Kongou Airlines runway, preparing to leave to the outside for body readjusments, Kuroko gives her the four leaf clover she found those many days ago for good luck. And thus, the fellowship, though bound by frienship and love, part ways.

Index Arc

 * Main article: Index Arc

Her debut was in the 1st arc where she is on patrol investigating some strange incidents happening in the city due to Stiyl and Kaori in the Anime. This is not in the Light Novels.

Sisters Arc

 * Main article: Sisters Arc

She makes her first appearance to Touma in the 3rd volume where she's shocked to see Mikoto is with him, giving him a threat to not lay a finger on her. Later, when Touma decides to investigate the Level 6 Shift Project she meets him again at the dorm where she manages to hide him away from one of the dorm supervisors.

Kazakiri Hyouka Arc

 * Main article: Kazakiri Hyouka Arc

Kuroko is seen hunting down Sherry Cromwell, who had entered the city illegally, and tries to apprehend her but is stopped by her golem. She is saved by Mikoto who also happens to be on the scene. She later appears to help the people stuck in the underground part of the city, teleporting civilians out of the area as Anti-Skill is preparing to fight against Sherry.

Tree Diagram Remnant Arc

 * Main article: Tree Diagram Remnant Arc

Kuroko faces off against Awaki Musujime who has a remnant of the Tree-Diagram, but is out-classed as Awaki proves to be the better teleporter. Awaki teleports a corkscrew into Kuroko's side, as well as several spikes. Kuroko returns the favor back at Awaki during their second encounter, but due to Kuroko being on the move all night without rest, she finds she cannot teleport anymore and ends up being pinned under a pile of furniture. Despite this, she continues to verbally assault Awaki, whose composure and teleporting abilities begin to break down as her psychological state of mind is rattled by Kuroko's taunts and rebuttals. Kuroko eventually manages to summon enough strength to overcome the the furniture pinning her down and stand up to face her now-panicking opponent. Using a lamp as an improvised weapon, Kuroko charges at Awaki; the latter reacts by pulling out a gun and shooting her in the torso. Awaki, who is by then in the grip of a mental breakdown, decides to crush Kuroko by collapsing the upper floors of the building onto her. Kuroko, who is almost completely incapacitated and barely conscious, only just manages to be saved by Mikoto (who used her railgun to tear open an entry point into the building) and Touma (who grabbed Kuroko and then used his Imagine Breaker to stop the teleport). Kuroko is then taken to the hospital.

At the hospital, Touma visits to see how she is healing up, and accidentally walks in when Kuroko is changing clothes. He is rewarded with a slap from Kuroko. Later Kuroko jokes that Touma likes girls who are less aggressive, but after seeing Mikoto take the suggestion seriously, she gets upset thinking Mikoto really has fallen in love with Touma. Kuroko vows silently to herself to get stronger herself so that Mikoto will rely on her more, and not be a burden after the 'Tree Diagram Remnant' incident.

Daihasei Festival Arc (Index)

 * Main article: Daihasei Festival Arc (Index)

Kuroko is unable to participate in the Daihasei festival due to her injuries from the Remnants incident, and is in a wheelchair during the course of events, escorted by Uiharu. She is seen to cheer up for Mikoto who is taking part in a competition between schools. After seeing Mikoto taking care of Touma on a public TV screen, she vows to kill him for taking advantage of Mikoto and stealing her rightful place.

Academy City Invasion Arc

 * Main article:Academy City Invasion Arc

Kuroko is next seen doing office jobs with Kazari Uiharu and wonders about the strange situation in Academy City, although she is shown to be aware of the news of an intruder due to television announcements.

Ichihanaran Festival Arc

 * Main article:Ichihanaran Festival Arc

Although mentioned several times before, Kuroko reappears again in the novels at last and debuts silently in Shinyaku Toaru Majutsu no Index. She appears with Konori Mii across the road where Uiharu Kazari is. As members of Judgment, it is her duty to aid Anti-Skill during the Ichihanaransai. She witnesses Mii calling out to Aogami Pierce for questioning, deeming him to be a suspicious person. Kuroko asks her on why they couldn't just throw him into a cell, as there are cases and mysterious reports that are needlessly driving down their efficiency, especially about rampaging Rhinoceros beetles. Mii says not to take her frustration on Aogami, to which she then asks for his belongings to check them.

That was the 43rd time he has been question by authorities that year.

Toaru Majutsu no Index Movie: Miracle of Endymion
Kuroko, still in a wheelchair from her fight with Awaki, first appears in a family restaurant, and makes a scene there, only to be shocked by Mikoto.

She later reappears with the rest of the gang, accompanying Meigo Arisa as she goes to a photoshoot. She rants about Ladylee Tangleroad not being the real CEO of Orbit Portal Company, and comments on her queer existence. She later, much to her shock, meets Ladylee herself, initially thinking of her as a doll, as she greets Arisa. Kuroko is with her camera as the bombing of the mall they were in begins, and teleports Ruiko and Kazari quickly away. She later returns to the scene of the accident, asking if anyone is hurt, but then discovers that a miracle has happened, and everyone is unscathed.

She later teleports Mikoto towards one of the bridges that leads to Endymion during the climax of the movie, allowing her to destroy a large mobile weapon that prevented Anti-Skill from entering the Endymion, as they have discovered it has been sealed. Mikoto tells Kuroko to stay put as she is still injured. Kuroko is forced to acquiesced as her injuries act up again. She later teleports to Anti-Skill's command post as Kazari discovers that Endymion is about to collapse and they need to destroy the explosive bolts to break it away. Kuroko offers to help Mikoto, but her injury prevents her from doing so. Tsuchimikado Motoharu later contacts them to be a volunteer in destroying one of them, though later has Stiyl Magnus do it instead.

Later, when Anti-Skill is too overwhelmed by Endymion's defenses to even get near one of the explosive bolts, Misaka 10032 contacts them, stating that they will aid it. Kuroko become confused as she refers to herself as Misaka, though no more comment is made of this.

Ookami-san and her Seven Companions
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.

References in other media
In Episode 6 of the second season of the anime ''Haiyore! Nyaruko-san W'', Cthugian Kuuko plans to have a baby with the male main character Mahiro. Trying to combine their both names, Kuuko proposes to name the baby "Kuroko". After that, she says "If it's a girl, we'll enroll her in Academy City."

Teleport
Her ability is Teleport (空間移動 (テレポート)  能力者) 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.

Not only is she able to teleport objects inside designated targets, allowing her to "throw" the darts she carries on her thighs with perfect accuracy, but she can also change their resulting orientation, shown when she teleported a standing Uiharu above a standing Mikoto such that their heads would collide. 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 the skills she learned from training, which emphasizes throws and take-downs that compensate for her small size. Kuroko specifically focuses on drop kicks.

Other abilities
Although usually displayed and used as comedy relief, Kuroko displays a strong constitution, surviving constantly shocks from Mikoto, 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 Awaki, from which she recovers quickly.

Misaka Mikoto
She has been in love with Misaka for a long time, whom she calls "Onee-sama" (big sister); when she has the chance she keeps a constant lookout for a chance to get physically intimate with Misaka (getting called a pervert and electroshocked in the process), and tends to get jealous if someone else gets her attention. Despite her overzealous attempts at gaining Mikoto's favor, her affections appear to be genuine; it has been shown on a few occasions that she is genuinely in love with Mikoto, even allowing herself to get severely injured and hurt in order to help Mikoto. She is regarded as Mikoto's best friend.

Kamijou Touma
Kuroko's relationship with Touma is mostly rivalry and jealousy over his encounters with Misaka even though Touma himself is not aware of this.

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.
 * 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 spikes are labeled with "Kuroko"