The story takes place in the Yan State during the Spring and Autumn Period and the Warring States Period. A demon fox from the far north transformed into a beautiful woman and caused trouble in the palace. She killed Queen Yan and fled without a trace. However, she reappeared in the capital of Yan four years later... Is she really the murderer of King Yan? Why is she doing this? Who will be her next target? Will she be caught?