Kōki Mimura is a male character with orange-brown hair styled in a crisp bowl cut and vivid green eyes. He wears a white button-down long-sleeved shirt paired with a black tie, grey trousers secured by a black belt with a silver buckle, and the school’s standard loafers.

Mimura wields the cryogenic ability "Ice Body," granting him mastery over generating, shaping, and precisely controlling ice, snow, and subzero temperatures. His signature techniques range from razor-sharp Ice Shards and piercing Ice Beams to defensive Ice Pillars, swift Ice Slides, chaotic Blizzards, and the immobilizing Deep Freeze.

Naturally friendly and unassuming, he prioritizes maintaining harmony among his classmates. An ardent filmmaker, his talent shines in projects like the covertly assembled documentary during the Okinawa Summer Course assassination plot. In humorous exchanges, he often serves as the sharp-witted "tsukkomi," countering absurdity with deadpan retorts.

His closest bonds lie with Taiga Okajima and Sōsuke Sugaya, united by their shared passion for artistic creation. Though quietly drawn to Yukiko Kanzaki, his reserved demeanor keeps his feelings discreet.

A strategic thinker, Mimura’s ingenuity proves vital in outsmarting adversaries, crafting inventive plans that leverage both his powers and intellect. His unwavering loyalty and collaborative spirit fortify the class’s unity, cementing his role as an indispensable pillar of their collective resilience.