After losing his wife, father-in-law Tohru began living with his son Kensuke and daughter-in-law Saki. However, Tohru constantly stared at Saki with disdain, his hostility growing stronger each day. One day, her husband departs for a business trip to Kyushu, leaving Saki alone at home with her father-in-law for the first time. He forcefully advances on her, and though Saki resists, her resistance eventually crumbles—unable to overcome his overwhelming desire. In his eyes, he sees only the ripe, mature body of his son's wife. A full-scale NTR (cuckold) incest drama unfolds between father and son over the married woman.