A man in armor with the power of darkness, Ares the Dark Knight, was heading to the Demon King's Castle as a member of the Brave Party. Hoping to defeat the Demon King and make a triumphant return to the hometown of Lulua, the hero's wise younger sister… And in the midst of the final battle, just as Ares delivers a dark blow… with signs of being taken somewhere, out of nowhere something takes you to another world. It feels like you've been caught up in a battle royale, in which strong people from various worlds participate!? To return to the original world with Lulua, who was separated, the dark knight Ares fights.