Shirou Kokufu assists Sarina Togo in the Wellside team, a Kura division operating the Mizuhanome System. He possesses a relatively short stature, gray hair, and violet eyes. Professionally attired, he typically wears a black suit with a dark gray shirt and lighter gray tie, accessorized with a black earpiece and carrying a handgun; for formal events like funerals, he switches to a black suit with a white shirt and black tie.

Kokufu demonstrates reliability and efficiency in his duties, maintaining consistent focus. His trustworthiness led to his promotion from a lower rank to Chief of Kura. Analytical skills, sharpened in Wellside, enable swift adaptation to investigative tasks. Under stress, visible nervous tendencies emerge, such as adjusting his tie or sweating. Personally threatening situations provoke pronounced reactions—intense fear when trapped in an id well and significant shock upon learning of Togo's relationship with Momoki.

His background centers on supporting Togo within Wellside, analyzing id wells—digital representations of a killer's subconscious. Following the events of FILE: 13 Channeled II, he becomes Chief of Kura, succeeding Takuhiko Hayaseura. As leader, he exhibits effective organizational abilities and strategic planning during crises, prioritizing mission-critical objectives like locating the wakumusubi above other concerns.

Kokufu evolves from an analytical support role to a decisive leader. This promotion reflects his competence in managing unforeseen events, though his occasional emotionally detached demeanor when issuing orders contrasts with his underlying stress responses. He appears in nine episodes.