Sota, who married the daughter of the Ohara family as a son-in-law, was fascinated by the abundant breasts of her mother-in-law, Rio. One day, Sota helped Rio stretch. Sota, who has reached the limit of patience with the obscenely shaking huge breasts in front of her, attacks Rio. And Sota, who also saw the weak personality of Rio, seeks Rio further. The actions of the two escalated, such as playing with Rio's naked body full of bubbles in the bathroom, hiding in a family gathering and immersing himself in affair.