There this two siblings who want to continue their study at seoul. But one day, one of them involved on a car accident. 

Lee Soonkyu the one who involved the car accident have been detained in the hospital. Before he's in coma, he had one wish for his sister "Lee Sunny" to be as him at his new school. Why he want Sunny to act like him? What could it be the reason of her brother want her to pretend as a boy.