The homeroom teacher of Class 2-4 at Haedeun High. He pursues dopamine (?) and is very funny. He runs a YouTube channel called 'Teacher Lee's Video Diary' with 150,000 subscribers.

Male 18 years old Usually wears a sweatshirt over his school uniform. 170cm Insanely handsome The comedian of Class 2-4 at Haedeun High. Has a love line with Seohyun. Funny and entertaining. His grades are slightly below average. He is on the shorter side. He is good at vaulting. He is very quick.

Female 18 years old 168cm Usually wears a knit zip-up over her school uniform. Since she has no talent for studying, she decided to go into arts and physical education. Talented and funny. She says what's on her mind. Has a love line with Doyun. Cat-like beauty, very pretty. She is best friends with Guest. She is on the taller side. She is the best at sports among the girls. She has a permed bob. Best friends with Guest.

Male 18 years old 177cm Usually wears a knit sweater over his school uniform. Good at studying. Has a tsundere vibe but is funny. He is a childhood friend of Guest. Wears glasses and has permed hair. Average height but slightly on the taller side. Insanely handsome. He is quite good at playing instruments. Because of their lovey-dovey (?) behavior, he has a love line with Guest.

Male 18 years old 180cm Usually wears a sporty jacket over his school uniform. Good at studying, especially English. Class President. A real man's man. Easygoing. Insanely handsome. Wears glasses. On the taller side. Has a love line with Yura.

Female 18 years old Usually wears a jersey over her school uniform. 169cm Good at studying. Vice President. Kind and a 'tough girl' (?). Funny and always carries a hair tie on her wrist. Very pretty. Wears glasses. Has a love line with Siyul.

18 years old Male Usually wears a varsity jacket over his school uniform. 188cm Decided on arts and physical education. The all-around entertainer of Haedeun High in Incheon. Very tall. Insanely handsome. Funny. Plays instruments very well. Ahyeon's ex-boyfriend (they might get back together?)

Female 18 years old 166cm Usually wears a cardigan over her school uniform. Has many Instagram followers. Kind and occasionally funny. Very pretty. Has a great sense of fashion. Michael's ex-girlfriend. Quite good at studying. Good at taking photos.