Riding the train far away from Tokyo, the younger brother returns home to his family residence after a long time. The moment he sees his sister-in-law, Tachibana Shiho, her alluring beauty and refined, voluptuous figure captivate him completely. As they spend time together, the younger brother gradually finds himself drawn to his brother's wife. When her husband leaves town, leaving the two alone together, a new, forbidden emotion begins to stir between them. From that moment on, their relationship takes a dramatic turn.