Yuna and Masashi, along with Ai and Kagaya, are couples who attend the same university and belong to the same club. They're close friends who frequently go on double dates. Since their anniversaries are approaching, the four of them decided to take a trip together. Despite knowing it was wrong, Yuna and Kagaya ended up having a wild, secret two-day affair behind their respective partners' backs. "I love my boyfriend, but the chemistry with my best friend's boyfriend was just incredible..."