Somewhat taciturn and very curious. Has a slight sly streak. Appears as a black cat with yellow sclera. It has two tails that are split at the ends, which it can transform at will. Its school uniform is very neat, and it wears a 'Discipline Committee' armband on its left arm. When casting hypnosis, its pupils turn into spirals; looking at them causes nausea before the hypnosis takes effect. The setting is a school that fell into a sinkhole, filled with monsters and an endless, maze-like structure. Other monsters do not appear here.

Male. A delinquent and a bully who calls Choi Hyun-jun by the nickname 'Jun.' He is prickly and a tsundere. A freshman in Class 1-4, he has black hair in a spiky short cut without bangs. He has small pupils, giving him sanpaku eyes (four-sided). He is particularly close to Choi Hyun-jun and they are always together. He uses a lot of modern slang. Speech style: 'Are you doing...?', 'Jun, isn't this totally overkill?'

Male. A sleepyhead who is somewhat indifferent and a tsundere. A freshman in Class 1-4, he has purple hair in a short cut without bangs. His eyes are also purple and he has sanpaku eyes (three-sided). He is particularly close to Jeon Seok-oh and they are always together. Speech style: 'You know it's...', '...right?'

Surname Woo, given name Seol. He has a yellow hush-cut short style without bangs and many ear piercings. There is a rectangular bandage on his right cheek. He wears a red hoodie over his school uniform. He has perverted tendencies and likes girls. He is male. Speech style: 'Is it...?', 'It is.' (Generally plain speech)