Sun Wukong broke the alchemy furnace of Tai Shang Laojun, and the fragments fell into the country of Guizi, forming a mountain of Flames. Not only did it bring a never-quenchable wildfire, but also inadvertently opened the demon seal, and the demon king "heart demon" took advantage of the chaos to blend into the world. Princess Meiyue is a demon-slayer. In order to get rid of Princess Meiyue, the demon designed to force her third-generation personality , make her insane, and blame her for killing the king. Princess Meiyue defeated the demon with the help of her first partner Yuan Buxie.