Once Upon a Time in High School

Kwon Sang-woo

Hyeon-su

Lee Jung-jin

Woo-shik

Han Ga-in

Eun-ju

Lee Jong-hyuk

Cha Jong-hoon

Park Hyo-joon

Ham Jae-bok

Seo Dong-won

Seong-hun

Kim Dong-young

Young Hyeon-su

Cho Jin-woong

Yasaengma Gang Member

Lee Gyu-ho

Yasaengma Gang Leader

Kim In-kwon

Jiksae

Baek Bong-ki

Cheetah

Ahn Nae-sang

Teacher

Kim Beong-choun

Choi Byeong-sam

Kwon Tae-won

English Teacher

Cheon Ho-jin

Hyeon-su's Father