Diavolo

デイアボロ

Diavolo rules over all demons, and everyone living in the Devildom knows his name. Even though his father, the Demon King, is still alive, he takes no interest in the affairs of the three worlds and has consequently granted Diavolo complete authority over the Devildom.
Consequently, it is widely accepted as fact that Diavolo will be crowned the Future King of the Devildom. For this reason, Diavolo has started to strengthen the Devildom's ties with both the Human World and the Celestial Realm through the exchange program, as he believes that the three worlds ought to coexist harmoniously.