The character known simply as Chief is the head of the detective division at the Inunari Police Station, which is the primary law enforcement body pursuing the titular art thieves. His full name is never disclosed throughout the series, and little is revealed about his life outside of work aside from the fact that he is married. Physically, he is depicted as a man of apparent senior age with black eyes and short, black hair that reaches his ears.

Chief serves as the direct superior to the two main police officers on the Cat's Eye case, Toshio Utsumi and Mitsuko Asatani. His primary role within the story is to manage the investigation from the precinct, acting as a source of constant pressure and authority over his subordinates. He is particularly demanding of Utsumi, holding him responsible for the team's repeated failures to apprehend the thieves and frequently scolding him for his perceived incompetence and clumsy handling of the case. This dynamic makes Chief a recurring source of comedic friction within the police force, as his exasperated reactions to Utsumi's antics are a running gag, especially in the early parts of the series.

Despite his gruff and often frustrated exterior, Chief's character is not without depth. As the series progresses, his development becomes apparent, revealing that his constant criticism is not merely from a place of annoyance but also stems from a genuine, if often hidden, concern for Utsumi's well-being and professional growth. This evolution transforms him from a one-dimensional authority figure into a more rounded character who ultimately cares for the members of his team. His motivations are rooted in a desire to solve the high-profile Cat's Eye case and uphold the reputation of his precinct, which drives his demanding nature.

One episode directly explores a personal aspect of his life, titled "The Woman the Chief Fell For," which focuses on him becoming infatuated with a beautiful woman who may be connected to a different thief known as Winter Firefly. This episode provides a rare glimpse into his life beyond the police station. As a superior officer, Chief does not typically participate in field work like his younger subordinates, but he is an integral part of the Inunari trio that faces the consequences of their collective failure, such as when a reshuffling results in the entire team being demoted to menial duties. His notable ability lies not in physical action or detective work, but in his authoritative presence and his role as the demanding administrator who oversees the main police characters, providing the structural pressure that defines much of their professional struggle.