Two girls, Chocolate and Vanilla, who live in the demon world, are not only good friends, but also candidates for the next queen of the demon world. They must enter the human world as competitors to compete with who can collect the most human hearts, that is, turn people's various emotions towards them into the crystallization of hearts. The person who collects the most valuable crystals will become the next queen of the demon world.
Chocolate, which was originally very popular in the demon world, and vanilla, which was inconspicuous in the demon world, completely reversed their popularity after arriving in the human world, leaving Chocolate in trouble. At the same time, Chocolate fell in love at first sight with Pierre, a young man of unknown origin, and her witch heart was attracted. It is said that every witch only has one heart. Once it is taken away, the soul will be lost forever. Can Chocolate protect her heart while passing the difficult Queen's Test to fulfill her dream? At the same time, the demonic villain race Ogar plans to occupy the entire world and attack the two queen candidates. Can Chocolate and Vanilla fight against Ogar? Can Chocolate be with Pierre? Who will be the queen of the demon world?