Oh Sehun is not somebody who opens up to people easily, he only has a group of friends and he does not have a girlfriend. He thought he was gay but when he accidentally kissed his friend it doesn't feel good. One day the empty house behind theirs comes someone to live in and this guy seems too friendly for Sehun's liking. 

On the other hand, Luhan, the chinese dude who lives in Korea for quite a while, notices how cold Sehun is. Luhan REALLY wants to be Sehun's friend. Best friend, or whatever. And he is trying his best to open Sehun's heart. With much determination, he knows he will succeed.