After Ten Millennia in Hell

Oh Kangwoo the Demon King has had it with ruling over Hell and wants to return to Earth. But when he finally gets there, not only are his powers sealed, but the Earth he once knew has turned into an MMORPG free-for-all. Dimensional gates have appeared all over the world, and "players" enter them to make a living by hunting monsters. If Kangwoo wants to survive in this dangerous game, he's going to have to level up, and fast. But for this demon king, hell on earth might be worse than Hell itself!

(Source: Tapas)