Eri Takigawa lives alone with her young son while her husband is away on a long-term overseas assignment. Hoping her son will grow up to be a respectable man just like his father, she enforces strict discipline, but his lack of progress only leads to mounting frustration and stress. With no sexual outlet, her pent-up desires grow unbearable, driving her to frequent masturbation. One day, her son's friend, Kenichi, catches her in the act. Seeing his erect cock, all her suppressed lust erupts uncontrollably. Pretending to be angry, Eri tightly grips his shaft and starts furiously jerking him off. The atmosphere shifts instantly, and their relationship takes a sudden, intense turn.