Kayoko Onikata serves as the section chief of Problem Solver 68, a notoriously troublesome club at Gehenna Academy where she is a third-year student. Her naturally intimidating facial expressions and appearance frequently cause others to misinterpret her as a delinquent, though she harbors no ill intentions. To avoid reinforcing this frightening perception, she refrains from addressing these misunderstandings.

Unlike her typically chaotic clubmates, Kayoko maintains a composed and reasonable demeanor, preferring to avoid unnecessary disturbances and passively participating in the group's activities. This inclination toward tranquility fuels her interest in metal music, which she uses to block out surrounding noise.

She possesses white hair with black bangs and a black ponytail secured around her horns, complemented by red eyes, pale skin, and a mole on her lower neck. Her halo forms a white pentagon with three sharp points and an embedded upside-down pentagon. Her attire includes a black hoodie emblazoned with "Born.To.Kill" in red letters, a standard Gehenna uniform (brown t-shirt and pleated plaid red skirt) beneath, and black sneakers with red accents. She carries a black bag with white seams over her right shoulder, housing a holstered firearm.

In combat, she wields a Heckler & Koch P30 pistol with a suppressor—featuring a silver slide, grey receiver imprinted with Gehenna Academy's name, and a silver grip. Her abilities specialize in crowd-control effects like "FEAR": *Fear Bringer* inflicts area-of-effect damage and FEAR; *Panic Shot* targets single enemies with a chance to inflict FEAR; *Scary Face* boosts her crowd-control power; *Can't be Helped...* deals bonus damage to crowd-controlled enemies. Her unique equipment, "Demon's Roar," further amplifies these crowd-control capabilities.

Operating within Gehenna Academy's chaotic environment, Kayoko's restrained personality contrasts sharply with Problem Solver 68's destructive reputation.