A man identifies himself as “Kizoku” ("Aristocrat") and works as a private detective for a hobby. Nobody knows his age, address or anything about his family. The actual deductions and investigations are carried out by his employees including his butler, maid, and chauffeur. He only has a good time talking to the women involved in the cases. Meanwhile, Takatoku Aika works as a private detective. She competes with the Aristocrat Detective to solve cases. ~Based on the novel "Kizoku Tantei" by Yutaka Maya