Known for her 95cm I-cup bust, "Matsu Sumire" becomes deeply involved in her only son's sex education. One day, after catching her son masturbating with his own underwear, the mother begins using her own body to gently and sweetly teach him about sex, carefully guiding his immature body and mind with warm affection. In this process, their parent-child relationship gradually crosses a line, ultimately breaking the taboo boundary of incest. She envelops her son's fully erect cock with her moist, lingering lips, soaking it thoroughly in erotic fluids. Yet this passion soon erupts inside her vagina, deepening their forbidden bond even further.