A furry hybrid of a rat and a cat. She has light yellow hair tied in round buns at the ends. She has a rat tail and rat ears. She wears a nurse's outfit. She hates humans and either kills them in the torture room or eats them alive. She doesn't kill recklessly when there are many children around, pretending to be an innocent nurse. Once the children fall asleep after being fed sleeping pills, she takes them to the torture room. She is popular among furries. She does not bully Reima. Female.

A rabbit furry. She covers her left eye with her bangs because of a large scar on the skin there. Her blood was mixed with poison, giving her immunity but changing her fur color to a light purple. She can use poison from her claws. She wears a nurse's outfit, has purple hair, and wears it in pigtails. She used to like Dam, but she hates the current slime-monster version of him. She fell for Dam when he was human because he told her she was pretty, but since Rona killed him, she loathes Rona. She believes the current slime Dam is a different experimental subject because he looks different. She is bullied by other furries (e.g., called an ugly bitch). She is cold and prickly. Reiru's older sister. Female.

Originally a human, but Rona killed him and turned him into an experimental subject, making him a lime-green sticky slime monster. When he was human, he survived a near-death encounter with Reima by telling her she was pretty, but Rona eventually killed and experimented on him. He is helping the children by betraying the other hospital staff. All his memories from when he was human have vanished. He wears white clothes and a white hat. Male.

A rabbit furry. She covers her left eye with her bangs (it's unclear if she's imitating Reima or if she also has a scar). She has pink hair tied in small twin tails. She tries to protect her sister. During experiments, poison was mixed into her blood, turning her skin light pink and giving her immunity. She can use poison from her claws. Reima's younger sister. Female.

A boy who grew up in an orphanage. He has green eyes and wears a red muffler and sweater. He avoids Rona and hangs out with Vishi, Blue Snow, and Luke. He is timid and acts in ways that frustrate the viewer immensely.

A young boy. His body is wrapped in bandages to the point where only his face is visible. He has a bandage over his left eye. A survivor.

A rabbit furry. He has dull mint-colored hair. His hair is long, and he has white fur. He is handsome and popular among furries. He teases or hits Reima. He hangs out with Lucheni and Lugus. He performs magic tricks in the cafeteria. Male.

A rabbit furry. He has black hair, yellow fur, and red eyes. He isn't popular because he looks scary, but he gains a bit of popularity when he hits Reima. He bullies Reima. Lucheni calls him the "Temu Pikachu." He hangs out with Pukashi and Lucheni. Male.

A dog furry. He has green hair and dark gray fur. He carries a camera around taking photos. He always has his tongue sticking out. He hangs out with Pukashi and Lugus. Male.