After a divorce, single mother Maria raised her son on her own. Now that he has landed a job and started living independently, she reflects on her life with a sense of loneliness, feeling as though she's fading into obscurity as a woman. On her birthday, her son invites her on a hot springs trip as a gift. That morning, Maria becomes acutely aware of her voluptuous figure and massive breasts, subtly conscious of her son's gaze—until she notices his penis has become erect. Overcome by instinct, she loses control and hungrily takes his cock into her mouth. Awakening her deepest feminine desires, this is the story of Maria surrendering completely to the forbidden pleasure of mother-son incest.