One day, Krystal, a normal girl without a father discovers she is actually the daughter of the president.

A love letter can change the meaning of a life.

What to do when you're used to being an average girl and one day, someone tries to kill you but Kim Jongin, that guy who has been always in your class saves you? What to do when he tells you that you'll have to do everything he asks you for or else you'll die?

You, who have known Yongguk for 8 years, meet the mysteious boy, Myungsoo. Soon, you'll start finding out a lot of things about him that will fascinate you. But what to do when your best friend doesn't trust him?

Your bestfriend who loves you, you, and the new guy who makes everything change.