Kuroko Shirai is a Level 4 teleportation esper attending Tokiwadai Middle School in Academy City. Her family name, Shirai (白井), means "white well," and her given name, Kuroko (黒子), combines "black" with the feminine suffix "-ko," referencing traditional Japanese stagehands dressed in black, reflecting thematic elements in her narrative. Her family runs a major convenience store chain, White Spring Holdings, subtly echoing the "white" part of her name. As a Judgment disciplinary committee member, she enforces peace in Academy City with a strict moral code and selfless dedication to justice. Her teleportation ability moves objects or herself within an 81.5-meter radius, limited to 130.7 kilograms. She carries metal darts strapped to her thighs, teleporting them precisely to immobilize targets. Initially unable to teleport herself, she mastered this skill after enrolling at Tokiwadai. Using her power demands intense concentration for spatial calculations, leaving it vulnerable to disruption. Kuroko exhibits a distinctive personality dichotomy. She holds a modern, future-oriented worldview, making her ignorant of traditional Japanese customs like the "love umbrella" ritual. She is blunt, skeptical of unscientific concepts like naturally occurring espers (Gemstones), and dismissive of urban legends until presented with evidence. Her most prominent trait is an obsessive romantic devotion to her roommate and best friend, Misaka Mikoto, whom she addresses as "Onee-sama" (big sister). This manifests in extreme physical affection, elaborate schemes for Mikoto's attention, and intense jealousy towards anyone close to her, particularly Touma Kamijou. Despite the comedic portrayal, her feelings are genuine, driving her to endure severe injury protecting Mikoto, often concealing her sacrifices to avoid causing worry. Her background reveals an early dedication to justice. She joined Judgment a year before entering Tokiwadai. During her first major case, she assisted senior Mii Konori in apprehending a bank robber with the "Equal Speed" ability. Despite being outmatched and injured, her persistence led to the robber's capture, aided indirectly by Mikoto's intervention. She later encountered Sha Danshan, leader of Tokiwadai's top clique, who stole a hairpin to replicate Kuroko's ability. Chronologically, Kuroko first appears investigating disturbances caused by magicians Stiyl Magnus and Kanzaki Kaori. In the Sisters Arc, she encounters Kamijou and helps him evade Tokiwadai's dorm supervisor while he investigates the Level 6 Shift Project. She confronts the magician Sherry Cromwell in the Kazakiri Hyouka Arc, but Sherry's golem disrupts her teleportation, requiring rescue by Mikoto; she later aids civilians underground during Sherry's attack. A defining moment occurs in the Tree Diagram Remnant Arc. She battles fellow teleporter Musujime Awaki, who overpowers her, impaling her with a corkscrew and spikes. Despite severe injuries and being pinned under debris, Kuroko taunts Awaki into a psychological breakdown. Awaki shoots her and attempts to crush her with collapsing building floors, but Mikoto and Kamijou intervene to save her. Hospitalized, Kuroko vows to become stronger to support Mikoto independently. This injury forces her into a wheelchair during the Daihasei Festival, where she witnesses Mikoto assisting Kamijou on public broadcasts, intensifying her jealousy. Later, during the Academy City Invasion Arc, she assists Judgment with office duties while monitoring citywide disturbances. She also participates in security operations for events like the Interceptor Show in the Document of Constantine Arc. Kuroko shares a close Judgment partnership with Uiharu Kazari, grounded in a shared promise to become full-fledged members together. Their bond stems from an early incident during the bank robbery case where Kuroko's rash actions led to Uiharu being taken hostage. Kuroko teleported Uiharu to safety but faced the robber alone, narrowly escaping due to Mikoto's anonymous intervention. This experience solidified her commitment to teamwork and responsibility within Judgment.