Reborn Octopus, Infinite Devouring Into Cthulhu

Su Yuan was reborn as an octopus, a captive one at that. Fortunately, he activated the system and thought he would reach the pinnacle of octopus status, but he was thrown into an inland river...

Many years later, Su Yuan finally realized his original dream of keeping all human beings in captivity.

Well, although humans don’t seem to call him that. They seem to call him the source of darkness, the ultimate disaster, the end of the world, etc.

(Unchanging Human, Evil God)