Lee Joon Yung, a pretty yet simple and kind-hearted girl. Kim Ha Jin,a cute girl who is loyal to her friends. This story is about two girls who happened to be besties, share everything in their life. They also make some silly promises to theirselves that is they will not be so close with boys. What will happen to them when a little changing of seats made by their seongsaengnim? Will they keep their promises? Or will they be friends/enemies with them? Or...will Joonyung and Hajin fall in love