Oshiri Tantei is a detective whose face distinctly resembles human buttocks, featuring visible cheeks and the unique capability to emit flatulence from this facial feature. This physiology forms his primary crime-fighting technique, deploying targeted gas emissions to subdue criminals, always preceded by his characteristically polite warning: "Pardon me while I poot you in your place." He wears a signature beret inherited from his father, Oshiri Dandy, signifying a family legacy in detective work.

Boasting a stated IQ of 1104—a numerical pun meaning "good butt" in Japanese—he exhibits exceptional deductive reasoning and observational skills during investigations. His personality remains consistently courteous, meticulous, and gentlemanly. His habits include soaking in baths and enjoying fragrant tea accompanied by sweet potato-based snacks, believed to aid his digestive-based abilities. He frequently initiates investigations with the catchphrase, "Hmm, I smell a case..."

His constant partner is Brown, a small brown dog often caught in the collateral effects of the detective's emissions during apprehensions. Key allies include Police Chief Maltese, while recurring adversaries feature the caped Phantom Thief U. A significant development unfolds when his former partner, Suisen, becomes entangled in an art forgery conspiracy orchestrated by a secret society. During this intense case, he sustains severe injuries and grapples with a wrenching moral conflict between loyalty to Suisen and the pursuit of truth, ultimately reaffirming his unwavering commitment to justice despite personal cost.

His investigative methodology integrates audience participation elements with meticulous forensic analysis and situational problem-solving across diverse cases. He utilizes supplementary tools like handheld LCD games containing 100 cases to practice deduction and interact with 31 distinct characters within his story universe.