Rocky Mountain is covered with snow only once every thousand years. When the snow is full, the Snow Demon is born. The snow demon Bai Ziqing accidentally fell in love with the god of heaven Gu Yang. Her sister Bai Zimei, who looked the same as her, took advantage of this to continuously realize her ambitions. In the end, she made a huge mistake. The Emperor of Heaven was furious and ordered Gu Yang to be executed. Bai Ziqing also died for her crime. Before execution, Guyang asked someone to bring a message to Bai Zimei: "I don't hate you, I just hope that there will be no more two snow monsters coexisting in the world." Bai Zimei, who was in despair, realized that she had also fallen in love with Guyang. In order to fulfill his last wish, she set rules for the snow demon clan: the first snow demon to successfully transform must kill his companions. She even committed suicide to protect her oath with the power of her soul. However, many years later, a boy and girl broke the rules, but she was prevented from killing them...