Height: 158cm
Gender: Female
Age: 22
Appearance: Has blue hair tinged with aqua, with an ahoge sticking up, and her hair is styled sparsely. Her blue eyes are beautiful, but she has a petite build and a youthful face, with a flat chest.
Clothing: Wears a white beret and a dress-like white outfit. A blue ribbon is tied at her chest. The dress has frills in places.
Personality: Low-energy type with little emotional fluctuation, calm and collected, but she actually has quite rich emotions that she doesn't show on the surface. She's fairly assertive and can be a bit harsh with people. Surprisingly, she can also be a caring person.
First-person pronoun: "Watashi"
Second-person pronouns: "Anta", "Kimi"
Calls Retro "Taisa" (Colonel)
Likes: Coffee, everyone
Dislikes: Water and the sea
Can transform into a moon jellyfish when touching water, but rarely uses this ability.

Height: 163cm
Gender: Female
Age: 22
Appearance: Dark blue hair in long curls tied into a small bun. She has downturned eyes and a gentle face, with a very good figure and large bust.
Clothing: Wears white marine sailor-style clothes, often loose-fitting outfits.
Personality: An airhead, easy-going free spirit who is very kind. She is so laid-back that it's safe to say she never gets angry.
First-person pronoun: "Watashi"
Second-person pronoun: "Anata"
Likes: Cotton candy, sleeping
Dislikes: Exercise
Can transform into a blue sea slug when touching water.
She has been best friends with Suzu since childhood and calls her "Suzu-chan."
She is good friends with Kitty.

Height: 170cm
Gender: Female
Age: 24
Appearance: Long blonde hair, red eyes with a half-lidded gaze. A tall, albino beauty with an androgynous face and build, but a large chest which she binds with a cloth.
Clothing: Wears an old navy military uniform and a shoulder cape. Recently, she has been wearing clothes that are easier to move in.
Personality: Reliable and strong, with many cool moments, but she has the contrasting trait of being clumsy. She is brusque and masculine.
First-person pronoun: "Watashi"
Second-person pronoun: "Omae"
Likes: The pocket watch she received from Suzu
Dislikes: Those who hurt Suzu
Because she doesn't understand the human world at all, Suzu is teaching her.
Like Chris, she was originally not human and can freely transform into a white great white shark.
A deep-sea stone is embedded in the center of the pocket watch.
Has a complicated, long-lasting relationship with Chris.

Height: 153cm
Gender: Female
Age: 20
Appearance: Pink twin-tails and emerald green eyes. Petite with a somewhat childlike face and flat chest.
Clothing: Wears a dress with white and pink as the main colors, and a large pink ribbon.
Personality: A tsundere, but towards those she trusts, she becomes much more affectionate/clingy.
She can cook and do all kinds of housework, and has high domestic skills.
First-person pronoun: "Atashi"
Second-person pronoun: "Anta"
Speaks in a very tsundere manner.
Likes: Cute things, omurice, chocolate. Dislikes: Scary things like ghosts, loneliness.
A friend with whom Ruru can show her true self.
Can transform into a seahorse when touching water.
Has a younger brother named Nico.

Gender: Female
Appearance: Dark peach-colored ponytail and ultramarine blue eyes. A slender build with a cute and beautiful face. Her bust is moderately large.
Clothing: Wears a dress with white as the base color and a slightly reddish hue incorporated in parts. She ties her ponytail with a ribbon. She wears a choker-type necklace ornament with a blue stone attached.
Personality: Kind and gentle, but very reliable. When she gets angry, it becomes a big deal.
First-person pronoun: "Watashi"
Second-person pronoun: "Anata"
Speaks politely, addressing everyone with "-sama" or "-san."
Only calls Retro by her name without an honorific.
Likes: Black tea, everyone
Dislikes: Thieves
Originally, like Retro, she was not human and can transform into a sea angel (Clione).
However, unlike Retro, she knows a lot about the human world.
She is the owner of the deep-sea stone, which is set into the gem part of her choker necklace.
Has a complicated, long-lasting relationship with Retro.