Due to his father's perverted desires, the mother has left the family, and into this broken household steps AV actress Haruka Koide as a new presence. In this strange new family setup, Haruka changes into an erotic swimsuit sent by a fan right in front of her stepson, deliberately stirring his arousal. Soon, the perverted father teams up with Haruka to forcefully grope and deeply kiss the inexperienced boy, escalating the bizarre situation. Strangely, the father urges his son, "Go ahead, touch your mother's big tits," pushing him to fondle Haruka's large breasts. Later, the son accidentally witnesses Haruka filming an explicit sex scene, driving his excitement to new heights. Eventually, with the father's approval, Haruka deflowers the virgin boy—an act culminating in a shockingly intense conclusion.