When a human appears in the Demon Realm, out of nowhere, and then declares he will become the next Calamity Lord, no one takes him seriously.
Why would they? Humans are the weakest of all the Races, with next to no magical power in their circuits. How could a Human ever, possibly, become the tyrant of Creation or, heaven forbid, obtain the Edict?
But Ain is not an ordinary Human. He passes on Emperor-level techniques like they are nothing and claims to know the current Calamity Lord... from two thousand years ago.
Who is Ain? Will he obtain the Edict this time around? Will he save his two goblin subordinates from crippling financial debt and murderous ex-wives?
Most importantly, there is no rule that says a Human can't become the Calamity Lord.