Two high school students, a girl,IU who is very optimistic about life and a boy, Daehyun who is always depressed because of a past accident are best friends. lU is always trying ways and means to make Daehyun smile again, even after many failures, IU believes that Daehyun will smile one day just like how she does everyday.

Baekhyun found something hiding under his blanket one day. He realised it was actually a girl. Who was it? What could she be doing here?