Aimi is depicted drenched in sweat as she becomes entangled with her ex-boyfriend Okuda. When he asks about her summer vacation plans, she tells him she's trying to mend her relationship with her husband and is going to a hot spring inn in Kusatsu. One day, she meets her husband's younger brother, Tsuyoshi, who suggests they go to the inn together. Though hesitant, she accepts his invitation and spends time with him at the inn. Drawn into Tsuyoshi's forceful advances, the situation takes an unexpected turn.