Three years into their marriage, the Kazama couple find their initial passion fading, leading to daily friction between them. Their sex life has become stale and monotonous, prompting the husband to buy a vibrator in search of new excitement. However, Yumi grows dissatisfied with her husband's reliance on such devices and ends up hiding the vibrator in the kitchen cabinet. One day, her nephew, Toshio, who recently returned from abroad, asks Yumi—fluent in English—for help with conversational English, and begins visiting her home. While practicing English, Toshio accidentally discovers the hidden vibrator. This discovery triggers unexpected changes in the couple's relationship.