Chiaki raised her only son, Takashi, single-handedly, maintaining a noble image of motherhood by balancing kindness with discipline. Takashi had always respected her, but their relationship would suddenly collapse due to an unexpected incident. A few days after Takashi told her, "Mom, I've got a girlfriend," Chiaki caught her son and his lover having sex at home. Witnessing the sight of her son's penis rubbing against his lover's vagina, a long-suppressed feminine desire within Chiaki awakens. Crossing the boundaries of motherhood, she begins to develop forbidden, new emotions.