Gyaruzuma Sex: Hoka no Otoko ni Inwai Houshi Suru Ai Suru Tsuma

The protagonist, Naohiro, and his wife Risa have been married for 4 years. Their married life is smooth sailing, and the good relationship between them is enough to be envied. Except for one feeling born from Naohiro's heart... It all started with a small incident. One night, when the couple was happily drinking together, Risa talked about her ex-boyfriend, and after the conversation, Naohiro felt a strange excitement. Feeling weird, he searched the internet about it, and while doing so, realized that he does indeed have "that" fetish. However, he can't possibly tell that to his beloved wife, but the more they find happiness with each other, the more stinging sensation torments him from within. Then one day, one of his juniors back in school, Tsukasa, consulted him about something...