Sarina Momonaga is married to a man whose father, a notorious womanizer, is already divorced from his wife. One day, Sarina accidentally encounters her father-in-law in the changing room and is instantly captivated by his strong, attractive physique and passionate lovemaking. Yielding to his advances, she begins an illicit affair with him. As their relationship grows deeper, Sarina eventually becomes pregnant with her father-in-law's child.