Hikari is the mother who divorced her husband when Hiroaki was in school, raising her child single-handedly. Working tirelessly, she supported Hiroaki through college, enabling him to successfully become a civil servant. With their finances now stable, Hikari quit her part-time job at the convenience store and finally had free time. However, she realized she hadn't had sex in over twenty years, and her pent-up desires were on the verge of exploding. Her target was Hiroaki. Perhaps it was resentment born from sacrificing her entire life for him. Overcome by the urge to take him, Hikari decided to invite Hiroaki on a hot spring trip...