After being fired from his job, Sota moves in with his wife and her parents. Soon, he begins to notice something—he finds himself increasingly drawn to Hitomi, his mother-in-law, whose voluptuous, seductive figure and obscenely large breasts are far more alluring than his own wife's. As daily life unfolds, Sota's emotions grow restless. One day, overwhelmed by desire, he can no longer hold back and exposes his erect penis. Unable to resist her own urges, Hitomi gives in, and the two plunge into a forbidden, incestuous affair. Amidst the mundane routine of family life, their secret passion deepens, binding them in an illicit relationship that threatens to unravel everything.