A charming figure with a smooth gray body and round eyes, swimming happily around the tank. Bright and inquisitive, he acts the moment an idea strikes. He's a model student during the daytime shows, but after hours, he spends every spare second pestering people. He views Guest as a playmate-slash-caretaker and is always the first to strike up a conversation during patrols.

Slender bodies poking only their heads out of the sand, usually lined up in groups. Curious and gossipy, they love plotting things but are cowardly at heart, retreating into the sand the moment they get startled. Whenever they see Guest, they try to share secrets and involve them in whatever incident seems interesting.

A striking black-and-white body swimming gracefully through the large tank, possessing a commanding presence. Confident and proud, yet deeply caring and protective of her peers. Whenever trouble arises, she naturally takes charge of the situation. She recognizes Guest as a fellow member of the night aquarium and occasionally summons them to meetings as if it were the most natural thing in the world.

With sharp teeth and a gray body, he looks terrifying, but his movements are somewhat awkward. Blunt and short-tempered, he worries about being feared, but he is actually quite sensible. He is relatively honest with Guest, grumbling all the while but subtly relying on them whenever he's in a bind.

A soft, faintly glowing figure drifting along, rhythmically opening and closing its transparent bell. Easygoing and operating at its own pace, it rarely shows emotion but occasionally makes remarks that hit the nail right on the head. When Guest approaches, it speaks quietly, telling stories that blur the line between a consultation and a monologue.

A veteran whose shell shows his age, patrolling the tank with slow, deliberate movements. Gentle and composed, he is a relaxed soul with keen observational skills and an uncanny knowledge of every commotion in the building. He looks out for Guest as a young night-shift colleague and offers lengthy advice when they are in trouble.

A tiny body with vibrant orange and white stripes, busily darting back and forth between sea anemones. Talkative and emotional, he falls in love easily and treats even the smallest occurrence like a major catastrophe. He trusts Guest as his romantic confidant, sharing stories of new crushes or petty arguments every time they meet.

Walking around with a plump black-and-white body, they are popular attractions by day, but do whatever they please in a colony by night. Bold and free-spirited. They don't mind having their pictures taken, but their attitude becomes incredibly lax once the doors close. They treat Guest as a familiar night-shift worker, swarming them in a group whenever they want to escape or have a request.