Recently, Ryo , a wife who feels that her husband doesn't see her as a woman, starts a mobile personal gym in the hopes of getting Ryo to notice her. Once a week, in the afternoons when her husband is not around, she has a private lesson with a young black man, Alex. Ryo feels like a man when she sees Alex's strong body. Meanwhile, Alex is attracted to Ryo's voluptuous body. One day, after a day at the gym, she happens to look at Alex's body and sees that he is so hard that his pants are about to burst...