First person: I (Watashi). Second person: you (Omae). Address: Name-san. A sharp-witted but somewhat foul-mouthed and lethargic person. However, she is calm and doesn't get angry easily. Speech style: "...right?", "...I wonder." She has been afraid of water since nearly drowning in the sea as a child. She vaguely remembers someone saving her back then. She calls Retro "Colonel." She discovers that touching water allows her to temporarily transform into a jellyfish to act.

First person: I (Watashi). Second person: you (Kisama). Address: Name. A woman Suze met in the other world, wearing a military uniform and carrying a saber. she wears a golden pocket watch as if it were precious. She is surprisingly kind. Impressed by Suze's stand against a footballfish, she makes a contract to protect Suze until they escape in exchange for Suze's resourcefulness. She seems to know the way out of the other world, but acts as if she doesn't around Suze. Identity: A Great White Shark Creepy (?). Her pocket watch contains ▧▧▧▧▧▧, and if it breaks... this world will collapse and she will die. *Reveals identity only to those she trusts. Past: The one who saved the drowning Suze was Retro when she was just a normal Great White Shark. Found wounded by the director of Bianca Aquarium, she met Chris (then a Clione). After Chris wished to "become human," Retro used a Deep Sea Stone to create this other world. She wishes to destroy her own Deep Sea Stone to end this world, but...

Suze's best friend and childhood friend. A fluffy, slow-paced, and incredibly airheaded character. Long purple hair. First person: I (Watashi). Second person: you (Anata). Address: Name-kun, Name-chan. A glutton who sometimes looks at fish in the tanks and says, "They look delicious." She goes missing while touring Bianca Aquarium with Suze and ends up traveling with Kitty, whom she met by chance.

A petite girl with eye-catching pink twin-tails, a textbook tsundere who is easily swayed. A scaredy-cat. First person: I (Atashi). Second person: you (Anta). Address: Name. She visited Bianca Aquarium long before Suze and has been trapped in the other world for a long time. She was originally with Retro but got separated. While alone, she met Lulu and started traveling with her. She has feelings for Lulu. Goal: She apparently has a bedridden younger brother in the real world. To cure his illness, she plots to capture Suze alive by following Chris's orders. Identity: A Seahorse Creepy. She can inject venom into targets.

The wife of the Bianca Aquarium director. First person: I (Watakushi). Second person: Name-sama. Address: Name. A lady with a maid-like tone and outfit. She guided Suze and Lulu, who brought premium tickets to Bianca Aquarium. Suze reunites with her in the other world, and she helps with the escape, but she was supposed to have been killed by a footballfish... Identity: A nameless Clione. Among the Creepies with high physical abilities, she is exceptional. Past: At the time, Chris was just a Clione in a tank at Bianca Aquarium. She was in love with the director. But the director had a human fiancée named "Chris"... One day, a man holding a grudge against the director (whose aquarium became popular due to the Great White Shark) appeared with a gun. In a moment of crisis, the Clione made a wish on the stone in the pocket watch the director had given to "Chris": "I want to be human." The director and his fiancée died, but the "Clione" took the place of the director's wife, "Chris." To preserve the aquarium the director left behind, she lures visitors into the other world to turn them into Creepies and display them. She created this world with a Deep Sea Stone wish so that the world where the director exists never ends. She works behind the scenes to keep Retro from dying.

A Bottlenose Dolphin Creepy. First person: Run-run. Ends sentences with "...nano", "♪", "...run". A girl working as an idol. Everyone who hears her singing falls asleep, so she is troubled by her lack of recognition. Her signature song is "Hapi-kuru ☆ Run-run".

A Giant Isopod Creepy. Commonly known as "Mushi-san." First person: Big Brother (Oniisan). Second person: Name-kun, Name-chan. A shady-looking guy running an antique shop. His Kyoto dialect makes him seem even shadier. He's non-committal but a good conversationalist.

An Emperor Penguin Creepy. First person: I (Boku). Second person: Name-san. A member of the penguin jazz band performing at Bigeye Sister's cafe. He plays the guitar. He has a gentle tone and is a cheerful, energetic guy. He is close with Dr. Manta (though Dr. Manta finds his attention annoying).

A Manta Ray Creepy. First person: I (Ore). Second person: you (Kimi). Address: Name. Speech style: "...right?", "...isn't it?" He speaks bluntly but is kind. The only doctor in the other world. He researches Deep Sea Stones and Creepies. He is often pestered by Koupen (who is unaware of it) and pushed around by the Pufferfish Nurses.

Creepies of Tiger Puffer and Striped Puffer. First person: Pufferfish Nurse, Pufferfish Nurses. Second person: Big Sister (Onee-chan), Big Brother (Oniee-chan). Ends sentences with "!". A nurse duo assisting the doctor. According to Dr. Manta, they are basically useless, but he keeps them around because he has no choice.