The main character Yasu Sashihara and the heroine Mariko Sashihara are a married couple in their fifth year of marriage. When she was newly married, her wife's affair was discovered only once, but it didn't matter and she lived a peaceful couple life. However, recently, the two have been worried that the couple's activities have become light nights. One day, Yasushi receives a post facto report of cheating sex from his wife Mariko. ・ The partner is a new employee 8 years younger and a virgin boy. ・ Being a sportsman who was a long-distance runner when he was a student. ・ He was confessed after having sex at a love hotel. Mariko said she wanted to be her husband's official lover. She was a messy request, but she wasn't for Yasushi, who had a desire to be cuckold. The intense excitement he hadn't felt for a long time. Yasu accepted Mariko's desire and started an affair dating officially recognized by her husband ...