By chance, Makoto and her fiancé, Saori, ended up staying at Rei's house. However, Rei, who seemed neat at first glance, was actually a ridiculous nymphomaniac. Under the same roof, a perverted couple and a young couple expose their sexual desires, and eventually they have a forbidden relationship. My friend's older sister who I've been interested in for a long time. The long-awaited opportunity is finally here...!