It's Really Hard to Be the Pain Demon King.

Jiang Wan traveled back in time to a world of heroes where slimes were jumping around and giant dragons were rampant. And he is the lord of a ruined Demon King's City - the Demon King of Pain. "Why is there so little magic power in my body... Oh, right, I can't bring pain to people at all..." Looking at a newspaper stolen from a surrounding town, Jiang Wu discovered that the living environment of the devil in this world is too bad! Fortunately, the dog system in his body can provide various kinds of help. But... Fearful skeletons? No, no, please change me to a claw machine... By the way, bring two bottles of Fatty Happy Water? Let the world feel pain starting today!