Nakata and Tanihara are from the same hometown and moved to Tokyo at the same time. Tanihara is a salesman at a real estate company, a fun-loving guy. Nakata works at city hall, and is the type who quietly gets on with his work and is more of an introvert. The two bump into each other while out and about. As they catch up on their recent activities, Nakata tells them that his sex life with his wife hasn't been going well lately. Hearing this, Tanihara has an idea: he invites the couple over to his house for a home party, where he plans to swap spouses, a swapping arrangement.