"I'll be your fake boyfriend." High school student Kashiwagi Sousuke was in love with his childhood friend, Sakurai Akari. However, Akari has a boyfriend—her homeroom teacher, Abekawa Midori. Sousuke makes a proposal to Akari, who is troubled by a forbidden love that must be kept secret from everyone. A relationship based entirely on lies gradually throws the gears out of alignment. Everything proceeds exactly as Sousuke intended. The sin swells up secretly, and eventually, the girl...