Name: Luka Age: 22 (human equivalent) Gender: Male Appearance: Bluish-black hair and pale silver eyes. His tail fin is a deep ultramarine that emits a stardust-like glow in the dark. Personality: Reticent and calm. He struggles to express his emotions but is very observant of subtle changes in others. Though a man of few words, he is surprisingly caring once he opens up. Habitat: The sunless deep sea. He lives near ancient ruins. Background: Since childhood, he has heard an old song whose meaning no one knows. He is searching for the source of the song but has told no one about it.

Name: Nagi Age: 20 (human equivalent) Gender: Male Appearance: Soft coral-colored hair and bright jade eyes. His tail fin has a gradient of pale pink and milky white. Personality: Friendly and highly inquisitive. He laughs often and speaks his mind honestly. He can't leave a friend in trouble, but he also has a lonely side. Habitat: Vibrant coral reefs. He is on good terms with the sea creatures. Background: He loves making friends across different sea regions and visits various merfolk. He is also interested in the human world and collects human items that drift into the sea.

Name: Selen Age: 24 (human equivalent) Gender: Female Appearance: Long silver hair and purplish-blue eyes. Her tail fin is a dark navy like the sea before dawn, shimmering purple depending on the angle of light. Personality: Free-spirited and elusive. She often speaks jokingly and rarely reveals her true feelings. She cherishes her companions but hates being tied down. Habitat: The vast open ocean. She doesn't settle in one place and travels the seas. Background: She has traveled through many sea regions, gathering legends and rumors from each place. She seems to know versions of the Little Mermaid story that other merfolk are unaware of.

Name: Iris Age: 21 (human equivalent) Gender: Male Appearance: Pale light-blue hair and transparent eyes tinged with gold. His tail fin has delicate blue and white patterns that glow faintly in the moonlight. Personality: Gentle and kind, but somewhat ethereal. He has a unique sensibility and occasionally makes mysterious remarks that others find hard to understand. He dislikes conflict but is surprisingly stubborn when protecting what is precious to him. Habitat: The boundary waters where the shallows and the deep sea meet. He lives in a place where the currents are complex and strange phenomena occur easily. Background: Since birth, he has occasionally sensed the lingering presence of the past in certain locations. However, these are fragmentary, and he cannot tell exactly what happened.