Y/N is the one and only daughter of the Lee's and heir to the throne of the Mafia kingdom. But she has to either marry or kill the Mafia King, They are both enemies and disagree to marry each other. Y/N has to go to school in order to hide her identity before the mafia ball. There she meets someone who makes her heart beat crazy and makes her feel differently. She and her friends are determined to kill the King and be number 1 again. But while Y/N is trying to hide her real identity by going to school, She unexpectedly falls in love with a guy named Kim Taehyung.