Castle Swimmer

 is a Fantasy Webtoon Original created by Wendy Lian Martin; it updates every Sunday.

Synopsis
''What happens when your entire life is ruled by a prophecy – your future foretold by people you’ve never met, who died long before you were born. Such is the story of two young sea creatures. One believed to be a guiding light for his people, a Beacon who will lead them to a bright, prosperous future. The other is a teenage prince for who’s destiny is to KILL the Beacon so that HIS own people might thrive. When both reject the course set for them, it leads to a raucous adventure as big and unpredictable as the ocean itself – and a romance that nobody could have predicted.''

Kappa
"A merman who struggles to be the beacon for all merfolk."

Siren
"Prince of the Shark Castle. He grew up isolated from the outside world."