Demon King Is a Hero is a Manga/Manhwa/Manhua in english language, SUGGESTIVE series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

The otaku Ren "accidentally" becomes a reincarnates and starts an adventure in Kenolan. In order to be free, Ren abandons god, and the ancient gods sent disasters to punish the Kenolan continent for this. In order to save Kenolan, Ren embarked on the road to resist the rule of the ancient gods.