Set in Asakusa, along the Sumida river amongst all the multi-tenanted residential and commercial buildings, there is a company by the name of "Ookawabata Tanteisha". It is a small private investigators' agency, run by 3 people. Muraki, who is the licensed investigator; the "Director", who has ties with the underworld; and Megumi, the candid and bubbly pretty receptionist. Their customers are from all walks of life, and some come with the strangest requests, and yet none are turned away. In the course of their investigations, they come in contact with the people related to the clients, and they end up trying to resolve their relationship problems.