The somewhat peculiar Hotta family runs Tokyo Bandwagon, a secondhand bookstore and cafe in the old part of Tokyo. They are a big four-generation family that is rare these days. The Hottas live by rather unusual family rules, and solve strange incidents that arise in the old town. 26-year-old Ao is the family’s second son, and a freelance tour guide. Although he is the child of his father’s mistress, he has been raised as the second son without prejudice. Ao is an irresistible playboy to females due to the gap between his frivolous behaviour and occasional melancholic expressions, but then he encounters university student Makino Suzumi and falls deeply in love with her.