In the land of Fronaldo, the Republic of Biscotti has been aggressively attacked by the Lion Kingdom of Garette. Facing potential defeat, Princess Millhiore summons a hero who can save the country. What she gets is Izumi Shinku, a middle-school boy from Japan. Awaiting him in Fronaldo is the task of becoming hero enough to defeat his enemies while learning the peculiar rules of battle in this strange new world.