Tatsunosuke Sakonji works as a police officer stationed at the Katsushika ward police box. He is frequently seen off-duty, wearing casual clothing while spending time with colleagues Kankichi Ryotsu and Hayato Honda, rather than in uniform.

Sakonji possesses a notably tall and muscular physique. He is a skilled practitioner of the Japanese martial art judo. A defining personality trait is his intense, unhealthy fixation on Saori, a fictional female video game character; this obsession forms a recurring aspect of his character across appearances.