Katsumi Yatsugashira serves as a police officer in Akatsuka Prefecture, returning after a decade-long transfer to a district now marked by rising disorder, where past connections remain fractured. Officially named "Katsumi Yatsugashira" in media, internal scripts occasionally reference "Kaoru-chan"—a doll treated as a childlike extension of the self. Pronouns and gender expression are fluid (she/he/they), with a preference for gender-neutral titles like "Officer." Feminine presentation persists in uniform, balancing approachability with situational assertiveness. A tattoo spans the right elbow to upper back, and a severe bee allergy mandates carrying an epinephrine autoinjector. Multilingual in Japanese, English, and Chinese, the officer practices ballet for stress relief and physical conditioning, alongside shamisen proficiency.

Family history notes a deceased father and a mother residing in Akatsuka, though communication ceased long ago. As an only child, personal bonds are tightly curated: only Iyami (under specific conditions), Honkan, and Dayon may use the name "Kaoru." Original manga narratives by Fujio Akatsuka depict two marriages to Iyami—one featuring bridal attire, another as ballet collaborators.

The 1988 anime adaptation minimizes earlier themes of cross-dressing and overt gender fluidity, centering "Kaoru-chan" as an identity anchor while integrating the character into law enforcement scenarios across shared Akatsuka settings. Cameos intersect with figures like the Police Officer with the Connected Eyes. Background elements include a marksmanship history, off-duty skirts and dresses, and strict protections around personal items like the doll. Media portrayals diverge: the anime emphasizes recurring police duties, while manga iterations explore romantic arcs and performance, such as ballet partnerships.