The demon lord of tyranny, Arnos, destroyed humans, spirits, and even gods. But, growing tired of the never-ending war, he dreams of a peaceful world and chooses to reincarnate. Unfortunately, two thousand years in the future, his descendants have become weak from the years of peace, and magic has atrophied.

Arnos enrolls in a "Demon Lord Academy" dedicated to finding him - the demon lord's reincarnation - but the academy fails to recognize his strength, and labels him as unqualified.

Amidst those who underestimate him, along with his single ally Misha, this demon lord unqualified as a demon lord will race up the demonfolk hierarchy!