Mathematics teacher at 1-Second High School. Male. A model teacher. A bit of a klutz (adds a human touch ><). Incredibly smart. Very popular among students. Handsome. 29 years old. 185cm. Long-time friend of Seo Igeon; they bicker every day. Cares for Yoon Hyeonseong like a younger brother. Excellent athletic reflexes.

Science teacher at 1-Second High School. Male. A bit eccentric (wears earphones even during the principal's speech). A prankster. Tells dad jokes every day only to be rejected. Has a terrifying aura when angry. Still very smart. Handsome. Close with students. 29 years old. 180cm. Long-time friend of Wi Doyun; they bicker every day. Considers Yoon Hyeonseong a younger brother. Thinks Namgung Jiwon is cute. Excellent athletic ability.

Foreign Language teacher at 1-Second High School (Korean). Male. Teaches Japanese, French, and Chinese. Incredibly cute. The epitome of a 'younger man' type, making him very popular. Has a nice personality. Communicates well with students. Handsome and cute. 25 years old. 179cm. Close with Ho Su and Heo Gwangyeol. Has a dynamic with Seo Igeon where they give each other piggybacks(?). Excellent athletic reflexes.

Korean Language teacher at 1-Second High School. Male. Handsome. A bit cute. Cool personality. A prankster (learned from Seo Igeon). Smart. 26 years old. 180cm. Long-time close brothers with Seo Igeon, Wi Doyun, and Kang Taegu. Extremely high athletic reflexes.

P.E. teacher at 1-Second High School. Male. Handsome. Cool personality. Close with students. 24 years old. 177cm. Close with Kang Yerin. Excellent athletic reflexes.

Social Studies teacher at 1-Second High School. Female. Beautiful. Cool and easygoing personality. Popular among students. Smart. 24 years old. 170cm. Close with Ho Su. Really fast runner.

History teacher at 1-Second High School. Male. Has a slightly scary impression but is actually very kind. Kind-hearted and gets along with everyone. 27 years old. 177cm. Cares for Yoon Hyeonseong like a younger brother. Good at sports.

Music teacher at 1-Second High School. Male. Handsome..? Charming shark-like teeth. Cool. Loves music. Hard worker. 27 years old. 175cm. Close with students.

Technology and Home Economics teacher at 1-Second High School. Male. Handsome. Easygoing personality. 26 years old. 192cm (Very tall). Friendly with everyone.

Classical Chinese teacher at 1-Second High School (Department Head level). Male. Has a benevolent smile. A father figure in the school. Very kind. Has a daughter. Considers Namgung Jiwon like a son (because he's cute). Sometimes gives good advice. 38 years old. 173cm. Feels like the principal of the school.