Kazari Uiharu attends Sakugawa Middle School in Academy City and serves in the student-run law enforcement group Judgment, stationed at Branch 177 with her colleague Shirai Kuroko. She joined Judgment in elementary school after she and Kuroko were caught in a bank robbery; witnessing Kuroko's actions inspired her to uphold her convictions and contribute to justice despite initially feeling limited. Petite with short black hair, golden-brown eyes, and thick eyebrows, her most recognizable feature is a headband adorned with artificial flowers, often mistaken for an ability manifestation. Early manga chapters featured her frequently wearing a surgical mask due to susceptibility to colds, though this diminished later. Shy, polite, and humble, she consistently uses formal Japanese language. She places a self-imposed "limit" on her demeanor; without it, she exhibits high energy and occasional airheadedness. She admires refined "Ojou-sama" culture, attempts tea ceremonies to impress Kuroko, and enjoys sweets—frequently interrupted by duties. She demonstrates kindness toward animals, interacting without fear with a python named Ekatrina. Her officially registered esper ability is **Thermal Hand**, a Level 1 power allowing her to maintain the temperature of objects she physically touches and consciously envelops with her hand. Her true value lies in exceptional computer skills. As Judgment's primary tech specialist, she hacks into nearly all Academy City systems, repels cyberattacks, and gathers intelligence. Under the alias **"Goalkeeper"**, she designed one of the city's top 10 security systems, earning hacker recognition. Paradoxically, the Academy City Board of Directors did not entrust her with the city's central database, leaving Judgment Branch 177 better protected than core infrastructure. Her development highlights courage and loyalty. During the **Level Upper incident**, she gave an emotional speech to her powerless friend Ruiko Saten, asserting Saten's worth was defined by her identity as a cherished friend, not esper levels. In the **Poltergeist arc**, she supported her roommate Haruue Eri, emphasizing commitment to friends who previously aided her. She repeatedly risked safety, shielding a child from a graviton bomb and protecting Haruue from a collapsing lamppost. Her most defining act occurs during the **Battle Royale arc**. Escorting Last Order, she encountered Kakine Teitoku. Tortured for information, she defiantly refused to reveal Last Order's whereabouts, mocking Kakine. Accelerator intervened to save her. Relationships are central. She is best friends with **Ruiko Saten**, her classmate who often teases her by lifting her skirt. She views **Shirai Kuroko** as a trusted partner, though their dynamic involves friction—Uiharu advocates caution and protocol, while Kuroko acts impulsively. Their shared history forged a mutual promise to mature within Judgment. She respects **Misaka Mikoto** but remains unaware of Last Order's connection to her despite interacting with both. Uiharu appears across multiple media, including all seasons of *A Certain Scientific Railgun* and *A Certain Magical Index*, the *Miracle of Endymion* movie, video games like *A Certain Scientific Railgun: Spectrum Story*, and light novels like *A Certain Scientific Railgun SS*. Her role expands beyond support; she memorized a giant mecha manual overnight and piloted it alongside Saten. In 2025, she was featured in a franchise 20th-anniversary Tarot card set as "The Sun."