Kazari Uiharu, a student at Sakugawa Middle School, serves in Judgment, Academy City’s student-run law enforcement. Her Level 1 esper ability, Thermal Hand, lets her maintain the temperature of touched objects, though she excels as a hacker and information analyst. She sports a flower-adorned headband, short black hair, and golden-brown eyes, with manga portrayals occasionally showing her in a surgical mask due to frequent colds.

Polite and reserved, Uiharu uses honorifics like "-san" while maintaining emotional restraint, yet reveals an energetic, airheaded side when these limits lift, such as during the Tokiwadai Dormitory Festival. Driven by duty, she bravely shields allies or confronts foes like Kakine Teitoku despite lacking combat prowess.

Her commitment to justice began in elementary school after a bank robbery rescue by senior Konori Mii, leading to her partnership with Shirai Kuroko in Judgment’s 177th Branch Office. She fiercely supports Level 0 friend Saten Ruiko, asserting personal worth over esper rankings during the Level Upper incident and defending Haruue Eri in the Poltergeist arc despite suspicions.

In the Battle Royale Arc, Uiharu aids Last Order in locating Accelerator. Tortured by Kakine for information, her defiance prompts Accelerator’s intervention. The manga highlights her adaptability as she alters her Personal Reality under pressure, disrupting an antagonist’s external energy sources.

Her growth balances technical skill—coordinating missions, hacking systems—with moral courage, facing armed criminals or enduring harm. Her bond with Kuroko evolves from friction to mutual reliance, solidified by a vow to mature after early missteps.

Fascinated by upper-class life, Uiharu practices tea-making to impress others and adores sweets, though duties often interrupt indulgence. Her calm demeanor around a pet python contrasts others’ fear, reflecting her animal-loving nature. These traits, paired with loyalty to justice and friends, define her multifaceted role.