This world is divided. We embrace each other and protect each other. We understand each other better than anyone else. We are not sisters, but our love is stronger than blood. She is a general who carries his father's ambitions, and he is the prince of an enemy country; she is a carefree and naughty princess, and he is her sworn elder brother; she is a rich girl who hides her secrets, and he is her mysterious fiancé; she is a decent saint, and she is an evil witch, and they were once good friends...