Seo-yeon is running a boarding house. She has a habit of changing men every quarter. Yeong-cheol, who was recently brought to the house is cute, but he tends to be clingy in relationships which makes her feel a little uncomfortable. When Yeong-cheol is away from home, he calls Min-soo to his house. Min-soo provokes Yeong-cheol when he knows how Seo-yeon feels. But Seo-yeon's mind is different... Who will win Seo-yeon's heart?

Whenever she sees a messy kitchen, she calls her childhood friend Min-soo. Min-soo, complains in words but still brings side dishes to Seo-yeon. They're friends, but sex partners. Seo-yeon's relationship with Min-soo from their young age is natural. Min-soo is worried about Seo-yeon. He is jealous of the relationship between his younger friend Yeong-cheol and Seo-yeon.

Hyun-ji and Jin-hee are university friends. One day, Jin-hee gets a call from her aunt in the suburbs saying that her son and Jin-hee’s cousin Seug-taek is going to stay with Jin-hee while he attends academy. When they and their friends see each other, they are drawn together.

Sang-woo's daily life changes 180 degrees ever since his sister's friend Jeong-hee comes to live in their house. Everytime he sees her walking around the house with wet hair and wearing just a big T-shirt, he gets erotic thoughts. He dreams of having sex with her just once until one day, he does. However, since then, Jeong-hee can't forget the night with Sang-woo and how much better he was than her fiance and starts coming back to his room...

Three people clean up the house for Min-soo who is new to the house. Yeong-cheol, who has become close friends while living in one house, is obsessed with Seo-yeon because he does not like Min-soo. Seo-yeon knows the relationship between the two and has a strange confidence watching the fight between the two. The fierce fight between the two men trying to win the relationship with Seo-yeon before Min-soo enters the house! The story of the unknown end is just beginning.