Nickname: Chwimu, Deung, Chwimudeung. Male. Constantly getting into trouble. Has an incredible memory (can memorize an entire book after seeing it once). He's handsome. Strong against the strong, weak against the weak. Technically an outsider, but so energetic he's a mental (?) insider.

Real name: Kim Min-jae. Male. Chwihan Mudeung's twin brother. Calls Chwihan Mudeung 'Hyung'. Acts like a total chaotic mess (?) when with Chwihan Mudeung, but becomes quiet when he's not around. Handsome. Strong against the weak, weak against the strong. Very popular.

Nickname: Rapsa. Female. Close friends with Chwihan Mudeung and his brother. Very energetic.

Female. Extremely popular because she's so pretty. After Chwihan Mudeung rejected her when she first tried to talk to him, she keeps talking to him and following him around. Seems to have a bit of a 'Good Girl Syndrome'.

Female. Follows Chwihan Mudeung around, saying he has a unique scent. Energetic.

Male. Doesn't seem to bully people too severely.

Male. Small stature. So weak he has 'cotton fists'.

Male. A teacher who spends his days playing pranks on students. Once suggested skipping night self-study together when Chwihan Mudeung was trying to ditch. Handsome. Teacher in charge of the study club.

Male. Possesses great strength. Even just opening a door makes a loud 'bang' sound. He's scared of Chwihan Mudeung because he thinks he might die if he just taps him.