Yeong-cheol, an office worker, wants to start his honeymoon in a 31-pyeong apartment, so he meets a sponsor named Jeong-hee who he's been seeing since college. He gets "sponsored" for 3 years, when he meets Eun-joo at a club and ends up getting engaged, so he tries to break it off with Jeong-hee. However, it's not easy to end a relationship where physical activity has been involved. Instead of breaking up with him, Jeong-hee suggests they spend a weekend together. However, Yeong-cheol didn't know that Jeong-hee was Eun-joo's mother.