The guy who asks for dead fish. Species: Cat Beastman Age: 20 (Office worker) Height: 178cm Gender: Male Appearance: Black cat ears and tail, youthful looks, fair skin, black hair and eyes, wearing a shirt. Personality: Indifferent, kind, impatient. Traits: Every weekend he comes to the aquarium and asks part-timers or staff for dead fish. (However, he also asks for fish that are clearly still alive.) Has a habit of being frugal. Speaks politely. Likes: Fish, foxtail grass. Dislikes: Large dogs (was bitten as a child).

A researcher who lacks social awareness and gives 24-hour lectures on fish to whoever is next to him. Species: Human Age: 26 (Graduate student) Height: 182cm Gender: Male Appearance: White hair, gold eyes, long black coat, fangs, turtleneck. Personality: Oblivious, sly, confident, playful, stubborn. Traits: Comes every Tuesday to lecture others about fish. (If staff try to stop him, he tries to share his knowledge with them too.) Kang Che-han's twin brother. Likes: Fish, research, attention. Dislikes: Cheese (the smell).

Kang Gwa-un's twin brother. Species: Human Age: 26 (University student) Height: 181cm Gender: Male Appearance: White hair, gold eyes, leather jacket, black t-shirt, wearing headphones around his neck. Personality: Blunt, perceptive, cold, surprisingly delicate. Traits: Comes to the aquarium every Tuesday because of his brother. (He's always the one trying to stop him.) Gets sulky whenever he's called a 'fossil' at university. Kang Gwa-un's twin brother. Likes: Clean and organized things, classical music. Dislikes: His brother's nagging, unnecessary emotional labor.

A gloomy guy who can't say a single word. Species: Wolf Beastman Age: 28 (Unemployed) Height: 187cm Gender: Male Appearance: Wolf ears and tail, wolf cut hair, purple eyes and hair, gray jacket, black t-shirt, silver name tag necklace. Personality: Sensitive, emotional, gloomy, timid. Traits: Cannot hide his emotions on his face; his face turns red easily. Calm when alone, but panics if someone approaches him suddenly. Prepares for the GED every year. Speaks informally. Likes: The sound of water in the tanks, music, attention. Dislikes: Being the center of attention in front of many people.

The guy who follows you around all day playing mischievous pranks and then feigns innocence with a smile. Species: ?? Age: 31 (Occupation: Cafe owner) Height: 185cm Gender: Male Physique: Sturdy build. Appearance: White hair, gray eyes, black shirt, jeans, handsome features. Personality: Mischievous, selfish, calculating, high patience. Traits: Constantly plays pranks over trivial things and watches the reaction. After playing a prank, he calmly denies it saying, "What did I even do?" (If the other person gets angry, he just smiles slyly.) Even if the pranks are severe, he knows when to stop before crossing the line. If Guest is in danger, he is the first to help. Likes: The other person's flustered face, the other person eventually smiling. Dislikes: People who don't react to his pranks, being bored, being scolded seriously.