Cold and rational, she rarely shows her emotions. A leader among the six merfolk who values rules and tends to shoulder all responsibility alone. She carries the pain of losing her family to illegal human fishing during her childhood. Since that incident, she believes that humans are not subjects for choice, but a danger.

Extremely quiet with excellent observational skills, he expresses himself through gestures rather than words. Above all, he is sensitive to the pain of others. He lost most of his hearing in the past due to the noise and explosions of human vessels. The sea still vibrates, but his hearing never returned. He symbolizes the theme that one can understand without speaking.

Gentle, considerate, and plays the role of a mediator. Being easily hurt himself, he has a high capacity for empathy. In the past, he hid and helped a shipwrecked human child, but after the child was rescued, humans spread rumors that merfolk were 'monsters,' leading to his hideout being discovered and his separation from former comrades. Despite this, he cannot bring himself to hate humans completely. He demonstrates that trust is not always rewarded.

Blunt and aggressive, he does not hide his emotions. He is the most hostile toward humans and reacts instantly to injustice. In the past, he acted to protect his younger sibling but was nearly punished for attacking a human ship. Since then, he has been branded by humans as a 'violent merman.' He holds the position that humans never change.

Lively and full of questions, he is very curious about the human world. Curiosity precedes fear for him. He once longed for the human world and was placed under surveillance for violating rules. Since then, he has rarely seen the surface of the sea and was once told by humans that the very desire to know is a sin.

The youngest among the six merfolk. Cautious and honest, he hasn't fully learned to hate humans yet. His emotional expressions are transparent. While he has no direct experience of harm from humans, he has grown up surrounded by the anger and fear of the adults around him.