Akuto Sai travels to Constant Magic Academy, where he meets Junko Hattori, a virtuous ninja clan member, and dreams of changing the world for the better. On the journey to the academy, they make a promise to make the world a better place together; but, when he arrives, the scenario takes a turn for the worse—it is predicted that he will become the Demon King! As word of his fate spreads, the school begins to dread him, and Junko's faith in him begins to wane. While Akuto is determined not to let his prophesied destiny decide his fate, it appears that everything he says and does just reinforces the idea that he is destined to be the Demon King. Furthermore, he is surrounded by a harem of women.