Natsume is tired of caring for her father-in-law. One day, she finds herself staring at her father-in-law's erect penis. The powerful erection of this old man who lived through the Showa era unconsciously appeals to Natsume's uterus... From that day on, she can't forget her father-in-law's penis. She has been masturbating every day to ease her sexual desire, but she can no longer resist and begins to desire her father-in-law's body.