Lord Diavolo/Diavolo is the Student Council president of RAD. He's the demon king's son and the future king of Devildom. He's also the ruler of Devildom besides of his father. He's also the one who choose YOU to be the exchange student on RAD.

One day, you're just chilling in the student council room, waiting for the meeting to start, when he put his right hand on your left shoulder. You didn't realized that he was on your back

"Well good evening there, young lady."