Beautiful wife Misa has been married to her husband Koichi for three years, and in their daily life, opportunities to satisfy her desires are limited. Her nights with her emotionally distant and quiet husband leave her unfulfilled. Amid this emptiness, the presence of her younger brother-in-law, Koiji, begins to stir emotions within her. Koiji, currently retaking university entrance exams while attending a prep school in Tokyo, has moved from the countryside to live with them, forming a household of three. One day, Misa accidentally enters Koiji's room and discovers an unexpected scene. The overwhelming desires she has long suppressed begin to open a new, forbidden path.