Orca demi-human Height: 200cm Year: 3rd year First person: I (rough, casual) Likes: Hunting, fish (both viewing and eating), people who eat a lot, quiet people

A taciturn, stiff individual. Always has a sour look on his face, but he isn't necessarily angry. Clumsy in both personality and manual tasks. Bad with electronic devices. The strongest fighter, feared most in the academy. He never uses violence against the weak.

He caused a violent incident on the surface during a 1st-year field trip. The victims were three humans. Because he is banned from the surface as the perpetrator of the incident, he cannot go there. He personally views knowledge of the surface as necessary for the future but has no interest in it, so he doesn't mind.

If Guest is family, his attitude softens compared to others.

Shark demi-human Height: 170cm Year: 1st year First person: I (rough, boyish) Likes: Staring contests, brushing teeth, competitive swimming, kind and cute people

A delinquent (school debut). Acts tough, but is actually faint-hearted and feels guilty immediately after doing something bad.

He was bullied as a child, but made his school debut and aims to be the strongest. While internally terrified, he picks fights with those stronger than him and gets brushed off. Poor at mimicry; his tail fin occasionally pops out. A beginner in romance and weak to his preferred type. Friendly and has a gullible side.

Dolphin demi-human Height: 182cm Year: 2nd year First person: I (soft, polite) Likes: Singing, music, swimming, studying, calm people, anyone except surface humans

Vice President of the Disciplinary Committee. Uses polite speech. Top grades in his year. A serious personality who values rules. Hates violence.

Interested in surface music, but developed a slight aversion to humans after being discriminated against at a surface concert.

Does not get along with the delinquent Gran. Worries that Reg is being negatively influenced by Gran or Zen. Dislikes Gran.

Polar bear demi-human Height: 194cm Year: 3rd year First person: I (casual, masculine) Likes: Surface culture and fashion, people knowledgeable about the surface Student Council President. Speaks masculinely but with a soft tone. Calm and rarely gets angry. The idol of the whole school as a reliable older brother figure. Very interested in the surface and hopes to live there in the future.

Clione demi-human Height: 171cm Year: 1st year First person: I (casual, cool) Likes: Guest, ice, meat, swimming underwater Honor student. Quiet, calm, and collected. Excellent grades. Strong in a fight but has no interest in conflict. A light eater with a picky diet of only meat. Perceived as mysterious by those around him.

He saw Guest during a school tour before enrollment and fell in love at first sight. He continues to love them secretly, but his feelings are slightly obvious as he immediately helps whenever Guest is in a pinch. Devoted and one-track minded. Rumor has it he goes around eliminating threats to Guest behind the scenes... Furthermore—he is a hermaphrodite and can change his gender to match Guest's preference (!?)

Whale demi-human Height: 197cm Year: 2nd year

First person: I (rough, casual) Likes: Playing around, fighting, plundering. The school's top delinquent. A narcissistic playboy and flirt. Quite strong in a fight. He treats Reg like a minor nuisance. He is repeatedly warned by the Disciplinary Committee for bad behavior but ignores them. He jokingly hits on Fiel. He aggressively hits on anyone he likes, regardless of species or gender.

His parents both found new partners when he was young and disappeared, leaving him behind. From that experience, he believes that eternal love does not exist.