A polite and meticulous super sleuth whose face resembles human buttocks, the detective known as Butt Detective operates in a world where this unusual anatomy is accepted as a natural trait. He sports a beret passed down from his father, Oshiri Dandy, and is known for his signature catchphrases, announcing “Hmm, I smell a case…” at the start of an investigation and declaring “Pardon me while I ‘poot’ you in your place…” before incapacitating criminals with a powerful blast of flatulence, a legitimate and effective technique in his crime-fighting arsenal. Despite his absurd appearance, he is a highly capable investigator with an IQ of 1,104, which is a playful pun on the Japanese phrase for “nice butt”. His fondness for sweet potatoes adds a whimsical layer to his character, aligning with his digestive-themed tactics.

Butt Detective is usually accompanied by his loyal partner, Brown, a small brown dog who serves as his professional assistant. Brown often finds himself on the receiving end of his partner’s gaseous attacks, providing a running gag throughout the series. The detective frequently collaborates with the local police, including the canine Chief Maltese and his K-9 officers, who rely on his sharp deductive skills to handle cases that stump conventional law enforcement. His primary rival is the master of disguise known as Phantom Thief U, a cunning thief who repeatedly challenges the detective with elaborate heists and narrow escapes.

The series is set in a whimsical, anthropomorphic world where animals and other creatures co-exist, and the cases range from simple thefts to complex international conspiracies. Early episodes feature straightforward mysteries, such as tracking down a candy thief or solving a string of burglaries, establishing the show’s formula of logical deduction and interactive audience participation, where viewers are asked to help solve puzzles like finding hidden objects or navigating mazes. Notable recurring antagonists include the Black Shadow Gang and a doppelganger who causes mischief around town, forcing the detective to clear his own name.

As the narrative expands, more complex arcs emerge. One significant storyline involves the international crime syndicate known as the Phantom Thief Academy, headed by the villainous Phantom Thief G, who advances a secret conspiracy called the Dark Age Plan. This arc sees Butt Detective going undercover as an idol on Stardust Island, forming a tentative alliance with his rival Phantom Thief U to retrieve the valuable Moonlight Stone and uncover the syndicate’s plot, which also reveals previously unknown details about Brown’s past. Another major case involves the antagonist Shiriarty, who orchestrates a series of crimes to steal a mysterious treasure known as the O-PARTS and plunge the world into darkness, forcing Butt Detective to collaborate with an investigator from the international police organization Wanterpol.

The series also delves into the detective’s personal history and family legacy. His father, Oshiri Dandy, an archaeologist and遗址保护 specialist, appears in several stories, including a jungle adventure where they must recover a stolen relic, the “Staff that Awakens Eternal Sleep,” from grave robbers. The detective’s backstory also includes a former partner named Suisen, whose involvement in an art forgery case at a metropolitan museum tested his ethics and commitment to the truth, forcing him to choose between personal loyalties and his duty as an investigator. Whether facing forgery syndicates, missing spices in a curry shop, or mysterious yetis on a ski slope, Butt Detective consistently resolves each case through a blend of methodical reasoning, inherited wisdom, and his uniquely flatulent brand of justice.