Miho left her job to become a full-time wife after marriage. Her husband Kentaro is the company's top salesman, but their sex life has grown stale and they barely talk at home. Then Kentaro's divorced boss Toru remarries Mao, a woman much younger than him, and constantly boasts about his bride. Noticing Kentaro seems down, Toru invites the couple over. That night both couples experience mutual cuckolding for the first time, and the thrill leaves them unable to stop. Their spouse swapping soon escalates into a four-person creampie orgy.