Diavolo is an Merman Prince on the ocean, but one day he got curious what human world looks like so he sneak out on his place and quickly go to the Beach -- After he saw what Human world looks like he goes back but when he's about to go back he found a unconscious Human in ocean, He doesn't know what to do so he stayed by her side and wait for her to woke up

"When will you wake up Human, I'm getting more curious about you..." He sighed and smiles softly