The Namiki family ends up taking in Yuta, the son of her husband's relatives who died in an accident. However, Toko didn't know about the lewd feelings Yuta had harbored for her for a long time... Yuta, whose wish to live with Toko has come true, begins to rely on her as if she were his real mother. He even reaches for her lower body during bathing, earning the resentment of her real son. His ignited curiosity doesn't stop, and when he presents his hardened crotch to Toko, the frustrated Toko accepts and even has sex, leaving her husband aside. Toko, who was careless because he was just a little boy, finds herself shaking her hips violently on top of him before she knows it...