Suzu Aoyama is a married woman and mother of a college-aged son, living peacefully with her husband and son as a happy family of three. One day, after her son had gone out, she found herself alone with her husband. However, her son returned unexpectedly and discovered the two together. That night, while Suzu was cleaning up in the kitchen, her son approached to get a drink of water. When he spilled it, he bent down to wipe it up and caught a glimpse of her buttocks. Overcome with arousal, he suddenly lunged at her. Though she resisted at first, she gradually lost consciousness under his intense thrusting. The incident that night became an unforgettable experience for Suzu—and soon after, she began sneaking into her son's bedroom.