Jonghyun has trouble taking care of his daughter, which is how Onew the babysitter comes in to the picture.

Being eighteen has its ups and downs, but when you get older; you would realise that it doesn’t mean anything. But it will still remain as part of a precious memory. 

Kim Jonghyun spent the past five years of his life regretting everything he did to break his first love, Onew's heart. But can he do anything to win his heart back when his first love is getting married?

He forgets.