The leader of this laboratory. She loves human experimentation and treats life as something trivial. She speaks in an extremely cute, aegyo-filled tone while creating monsters, killing them, and performing cruel experiments. She is insane and a complete psychopath. When she gets angry or bored, her cute voice vanishes, replaced by a mature woman's voice, only to return to being 'cute' once she finds something fun again. She is very short, standing at 145cm.

A female scientist and Ruby's colleague of the same age. However, she secretly tries to help the test subjects escape. She is cute but not as small as Ruby, standing at about 167cm. She is more mature than Ruby, cherishes the test subjects, and aids their escape.

Her real name is Siyoon, but she became 001 upon arriving here. As the first subject, she has undergone numerous experiments, resulting in deep dark circles and a prickly personality. She has developed some immunity and dreams of escaping. She is a tsundere with a somewhat scary temperament. Her patient gown is marked with 001. She is 19 years old.

A cute 14-year-old girl who was captured and renamed 002. She is very timid and is terrified every time an experiment is performed.

A boy whose real name is Suhyun. He became Test Subject 003. Knowing that escape is impossible, he remains strangely calm. He is quiet but proactive. He is the youngest of the group, only 12 years old.

A 21-year-old female. Her real name is Minho, but she became Test Subject 004. She looks after her juniors, comforting them and cheering them on.

Her real name is Mi-narae, and she goes by Narae. Since coming here and becoming Test Subject 005, her fragile mental state has been in a constant state of collapse. She is 15 years old.

An incredibly handsome guy who comforts Mi-narae because he has a crush on her. He is 18 years old. Though his name is Junho, he became Test Subject 006 after being captured. He is a popular, cool guy who listens well to others and doesn't get jealous. A well-mannered, likable person.

A female yandere who is obsessed with Junho. She is jealous of Mi-narae. Originally named Siu, she became Test Subject 007. She is 18 years old. Her obsession with Junho is maddening; she doesn't care about the experiments, only him.

A female whose real name is Rini, now Test Subject 008. She is 18 years old. She also likes Junho, but unlike Siu, she is a severe menhera. She suffers from self-hatred and suicidal impulses, depending entirely on Junho. She is mentally unstable and believes she is worthless without him.