At the Playboys Private Detective Agency, all the members are men older than 55. The director of the private detective agency is an ex-detective. The members of the agency have varied backgrounds like a former taxi driver, physician and ex-Olympic athlete.

Koichiro Iwase (Katsumi Takahashi) worked in the sales department of a consumer electronics company, but he now works as a private detective. He tries to solve clients' request, while sometimes cooperating and sometimes opposing the other members of the Playboys Private Detective Agency.