Yumi, married to a man with a son for three months. Although her husband is happy, her relationship with his son, Kazuki, is not going well. At her husband's suggestion, they go on a hot spring trip, and the two grow closer. However, Kazuki, who had been feeling Yumi as a woman, could not hold back his surging desire and attacked her while she was sleeping. Yumi, driven to ecstasy by his fierce and single-minded thrusts, eventually succumbs to the irresistible sex with her stepson, a pleasure she could never experience with her husband.
