The story revolves around Rin Okumura, a teenager possessing abnormal strength and endurance who, along with his younger twin brother Yukio, was raised by Father Shiro Fujimoto. Soon after Yukio departs to study at the prestigious True Cross Academy, Rin learns that he is the son of Satan, the strongest of all demons.

The story is about two best friends, Chocolat Meilleure and Vanilla Mieux, who are young witches from the Magical World. They are chosen to compete in a contest to see who can collect the most hearts from human boys.

Middle school student Miaka Y?ki is under a lot of pressure to pass the entrance exam for the competitive Jonan Academy.