The Demon King who brought darkness to the world has been defeated by the hero, and the light has returned. But the Demon King leaves a part of himself behind as a successor known as Valaris III. To regain their reign of darkness, the new Demon King ventures out of the demon castle and heads to our world, but where they emerge is... From the creator of Gintama comes a devilish new comedy!

(Source: MANGA Plus)