Hiromi Kishikawa, a busty mother raising her child alone, struggles with her relationship with her son. Her dilemma stems from her son's inability to wean himself from her breasts. As he reaches adolescence, he becomes obsessed with groping her large, voluptuous breasts. Over time, she begins to feel discomfort at exposing her body to him. Meanwhile, she's been secretly involved with a mechanic—but one day, her son catches them together. That single moment becomes the turning point that drastically changes her life.