At Rosewood Academy, Arnest Flaming the top student of the academy encounters a mysterious young boy called Blade, whose power dwarfs her own. The arc follows the situations Arnest goes through in order to reveal Blade's true identity who's peculiarly, the very first transfer student the academy accepts. With the King himself involved in his enrollment, Arnest grows more suspicious and decides to test Blade nd expose his true colors.
The mysterious demon sword that Arnest wields becomes more and more troublesome for the girl who fights its will with all her might. Failing to do so herself, and after being consumed by it several times, Blade decides to research the sword and finds a way to free Arnest from Asmodeus's curse. Setting up a ritual in the Royal Library of Banned Literature, Arnest confronts the demon in his own world and prepares for battle, finally defeating it and putting the sword under her full control.