Sota, who married the daughter of the Ohara family as an adopted son-in-law, was captivated by his mother-in-law Rio's voluptuous breasts. One day, Sota had to help Rio with her stretching. Unable to bear the sight of Rio's breasts swaying obscenely in front of him, Sota attacked Rio. Sota also saw through Rio's timid personality and continued to pursue her. Their actions escalated, playing with Rio's bubble-covered naked body in the bathroom and indulging in a love affair in secret during family gatherings...