Butt Detective, originating in Japanese picture books, sports a head distinctly resembling human buttocks. Eyes sit on each cheek, with a cleft replacing conventional facial features like a nose and mouth. This unique anatomy defines his identity across all media appearances.

He operates as a professional detective, characterized by meticulous attention to detail, logical reasoning, and a polite, sophisticated demeanor echoing Sherlock Holmes. His investigations typically involve solving thefts and minor crimes through systematic evidence examination and witness interviews. He frequently partners with an anthropomorphic dog assistant named Brown and interacts with recurring characters like a cucumber-like figure.

A signature ability involves deploying potent facial flatulence—described as a "stinky fart" or "facial flatulence"—to subdue cornered criminals during confrontations. Despite this comedic tactic, his portrayal remains serious and intellectually rigorous within his fictional universe, where his appearance is treated as mundane.

Beyond detective work, he maintains refined personal habits, relaxing in hot baths and enjoying tea with potato cakes while wearing a bathrobe, highlighting the contrast between his unconventional physiology and dignified conduct. In later media like the "Cosmic Front" specials, he partners with Mikku to solve cases integrating educational content on scientific topics such as dinosaur research and space technology.

The character has appeared consistently across multiple seasons since 2018, television movies, and specials. He maintains core traits while expanding narrative contexts—from standalone picture book mysteries to collaborative educational adventures. His methodology remains focused on analytical deduction, with facial flatulence serving as a recurring tactical resolution within the stories.