A girl named yn. she is a bubbly, cute, hot and savage at the same time .she is the most beautiful girl in her university and she is also a topper of class. her mother died when she was 10 after that her father raised her with his love. he is a buisness man of lee coperation..... What will happen when her new transfer professor is going to be her step-brother. Kim taehyung a cold,rude, handsome and have a short tempered . who is also a mafia king in underworld him being a professor is just for his passion but him being a mafia king for his parents his father was a mafia king and his father got attacked by his father enemy . after his parents death. he need to being a next mafia king and promise his father to take revenge from their enemy.... after that he started to live with her aunt (mom's sister) whom he called his second mother.... YN X TAEHYUNG FF