Chiharu, a wife forced into a relationship with her son. Under the strict, sadistic demands of her husband, she begins a physical relationship with her quiet, reclusive son. Initially tormented by guilt, Chiharu gradually finds her emotions stirred by her son's young, vigorous, and powerful body. With each touch of his penis, she grows increasingly conflicted yet overwhelmed by pleasure. Sensing his wife's shifting feelings, her husband intensifies his cruelty, subjecting her to harsher, more sadistic treatment. Soon, a forbidden relationship blooms among the three family members, and their illicit affair begins.