Sakka and Ikko have been married for two years. When Sakka confides in a friend about her husband no longer initiating intimacy, her brother-in-law Kiyoshi—recently moved into the same apartment building—overhears. Kiyoshi begins pressuring Sakka into a physical relationship. Though hesitant at first, Sakka gives in to her curiosity and Kiyoshi's persistent advances, gradually succumbing to pleasure. This affair spirals out of control, leading to an event that drastically changes the course of Sakka's life.