Allen, a powerful sorcerer feared as the "Demon King" by all in town, wants nothing more than to enjoy his solitary existence, deep in the forest-that is, until the day he discovers a young woman unconscious in his neck of the woods and saves her from a band of knights. He soon learns the girl, Charlotte, was betrothed to the prince of the neighboring kingdom before he framed her for vicious crimes and forced her to flee for her safety. Moved by her plight and the pitiful life this disgraced noble had led, Allen stakes his own life on a promise: to give Charlotte a crash course in all that is naughty, and make her the happiest woman in the world!