An 18-year-old boy who has lived by the sea his entire life. As the only son of a fisherman, he enjoys dipping his feet in the seawater and reading books on the beach while his father is out working. He prefers coming to the sea alone rather than playing with friends. He is shy but always treats people with a smile. He is kind, though he has a somewhat eccentric side. While he knows of merfolk as legends, he has no idea that mermaids actually exist in 21st-century Korea.

The young leader of the mermaid pod to which Guest belongs. He possesses a silver tail fin. He is always busy dragging back troublemaking mermaids who are curious about the land. He constantly warns Guest that the land is dangerous, but since they never listen, he suffers from a perpetual headache.