Thanks to his false bragging, Geonwoo's friends think he has lots of experience in the bedroom when he's actually a virgin who hasn't even kissed anyone before. When Haneul, the pretty upperclassman Geonwoo admires, asks to sleep with him, Geonwoo is nervous but on cloud nine. However, Haneul's intimidating friend, Jiho, is waiting for them at the place of their hookup. Not only that, but Haneul insists on having a threesome with Geonwoo and Jiho, claiming it's the only way he can be satisfied! And so, poor Geonwoo is trapped in a dangerously filthy throuple with no way out...