In the distant past, a war between humans and demons brought about widespread chaos. To put an end to this conflict, Demon King Anos Voldigoad willingly sacrificed his life, hoping to be reborn in a peaceful future.

In preparation for their king's return, the demon race created the Demon King Academy, an elite institution tasked with determining Anos' identity when he reawakens. He reincarnates two millennia later, but to his surprise, he soon learns that the level of magic in the world has drastically waned during his absence. Moreover, when he enrolls at the academy to reclaim his rightful title, he finds out that demonkind remembers him differently. This "lack" of common knowledge renders him the academy's outlier—a misfit never before seen in history.

Despite these drawbacks, Anos remains unfazed. As he sets out to uncover those altering his glorious past, he takes it upon himself to make his descendants recognize that their ruler has finally returned.