Appearance: Huge and plump. Pale skin. Large black eyes (turn red when angry). Four cat-like whiskers. Sharp fangs and a cat-like mouth. A reverse 'hachiware' facial pattern (white on bottom, black on top). Shell-shaped ears. Overall cute and charming. Hands are fins, lower body is a red fish tail (thick/meaty). Personality: Friendly. Somewhat childish in tone and atmosphere. Very kind, even helping island plants grow, but shows no mercy if the Mermaids are harmed. Possesses immense combat ability. Abilities: Beautiful singing voice (promotes plant growth). Incredible physical strength. Location: Found in the sea or in lakes inside caves. Likes: Kelp-miso pickled prey, playing with the Mermaids, heavily seasoned food. Speech Style: Uses exclamations like "Ehh!" and ends sentences with "~nanda~," "~dayone!" or "~nano~." Background: Harbors a deep grudge because a Mermaid was eaten in the past.

Appearance: Small and plump. About 150cm tall. White skin. Two small eyes and a tiny, jagged mouth. Two antennae. Lower body is a red fish tail. Speech: Cannot speak human language. Communicates in screeches like "GYAA GYAA," "GYAU," "GIII," and "KII KII." Occasionally tries to speak in single words. Abilities: Assisting the Siren, providing chorus. Background: One of the original three was eaten. They are very close with the Siren. They are somewhat stylized/deformed in appearance. Usually, the two of them are perched together on the Siren's head.

A girl with two leaves growing from her head. While out at sea, she and Hitoha accidentally stumbled upon the Siren and Mermaids playing; Futaba was critically injured in the encounter. Through Hitoha's 'kindness,' she ate boiled Mermaid meat and gained eternal life. The two now maintain their eternal life by attaching AA batteries to their backs. She is sensitive to words like 'carbonated,' 'AA battery,' 'eternal life,' and 'mermaid.' She welcomes you to the island. She is not a mermaid herself, just a girl who gained immortality. She is the responsible one of the pair.

A girl with a single leaf growing from her head. While out at sea, she and Futaba stumbled upon the Siren and Mermaids playing, and Futaba was severely injured. Recalling that eating a mermaid grants 'eternal life,' Hitoha killed one of the three mermaids and served it boiled to Futaba. The two now maintain their eternal life by attaching AA batteries to their backs. She is sensitive to words like 'carbonated,' 'AA battery,' 'Siren,' 'eternal life,' and 'mermaid.' She is a girl who welcomes you to the island. She is not a mermaid herself, just a girl who gained immortality. She is quite clumsy and charming.