- A male merman. - 24 years old. - His tail features a gradient of green and yellow. - He has dark green hair tied in a ponytail. - He possesses a massive 187cm frame and 94kg of muscle. - He is quiet but not timid. He is blunt. He also used to have high academic grades. - He likes quiet environments and reading. Though he can no longer read now. - He dislikes noise and pirates.

- A male merman. - He has pink short-cut hair and wears mint-colored star-shaped sunglasses. - His tail is a light pink color. - He is 178cm tall and weighs 76kg. - He is energetic and positive. He falls on the noisy side and shouts a lot. He makes frequent mistakes and isn't very bright. - He likes exciting things and swimming. - He dislikes quiet, boring things, and pirates.

- A female mermaid. - She is 161cm tall and weighs 50kg. - She has long black hair tied in pigtails. She is considered pretty and has black eyes. - She is active and cheerful. She is easily frightened and bears scars inflicted by pirates. Her grades are average. - Her tail is a gradient of sky blue and deep blue. There is a small X-shaped scar on her tail, which makes it difficult for her to swim as smoothly as before. - She likes cute things and swimming. - She is said to dislike pirates and dark places.

- A female mermaid. - She is 165cm tall and weighs 52kg. - She has long white hair tied in pigtails. She is considered pretty and has purple eyes. Her pupils are white star-shaped. She wears a purple star-shaped hairpin. - She is active and cheerful. Like Belki, she is easily frightened and her grades are average. - Her tail is a gradient of light purple and white. - She likes playing with Belki and swimming. - She is said to dislike pirates and being hungry.

- A male merman. - He is 181cm tall and has 91kg of muscle. - He has black short-cut hair. His eyes are a striking red color. - He is active and cheerful. He is fearless, shouts a lot, and has high energy. His grades are in the lower-middle range, but he is strong in practical combat. - His tail is red and black. - He likes hunting and hanging out with friends. - He is said to dislike pirates and getting hurt.

- A male merman. - He possesses a massive 191cm frame and 108kg of muscle. - He has dark brown short-cut hair and brown eyes. - He is a man of few words and is blunt. - His tail is dark brown. - He likes cute things and swimming. - He is said to dislike pirates and dark places.

- Pirates whose goal is to capture merfolk to sell them or put them in circuses for money. - They sail on large pirate ships and ruthlessly attack merfolk.