Takagi and Yui have been married for four years. A year ago, his parents divorced, so he took his father to live with him. His father is a long-distance truck driver and is often on leave, so he spends a lot of time with Yui. He often says obscene words and touches Yui's body. Although Yui told him back, because she thought her father was just teasing her, Takagi didn't pay attention. One day, coming home from work, Yui seriously told him that his father had touched and sexually assaulted her. At first he was very angry and decided to move out. But the curiosity and excitement of knowing his wife was having sex with someone else made him even more uncomfortable. He discovered he was a cuckold. He told Yui and Yui finally accepted this. He asked her to seduce and make love to her father again so he could witness. Although hesitant, out of favor, Yui agreed. So the two returned home, ate, drank and played cards. At that time, Takagi would pretend to be sleepy so he could sneak out and watch his wife and biological father make love together...