Bacchiri, a young boy with prominent jug ears, works at a poorly managed detective agency as its primary investigator. He solves cases that baffle authorities through clever thinking and resourcefulness, employing an ingeniously brilliant mind to unravel each mystery. He receives operational direction from the agency's president, Gappori, and collaborates with the head detective, Chibisu. Two anthropomorphic animal companions assist Bacchiri: Roba, a donkey characterized by wearing overalls, and Benko, a parrot. Both accompany him during investigations and case resolutions. The narrative presents each case as a self-contained mystery encountered during his daily agency work.