Mitsuyo started yoga to make up for lack of exercise. Her husband was excited by her appearance and they enjoyed sex for the first time in a long time. On another day, Mitsuyo started yoga again and changed into leggings. This time her son was excited by her appearance and his crotch throbbed. Mitsuyo, unaware of her son's arousal, invites him to "exercise together", but her son is aroused. Unable to resist the many radical poses of his mother, he goes wild, saying "You're trying to seduce me!" He pushes his mother down and rapes her. From that day on, the son sneaks around his father's eyes and seeks Mitsuyo's body...