Once Upon a Time in High School— Full Cast

Kwon Sang-woo

as Hyeon-su

Lee Jung-jin

as Woo-shik

Han Ga-in

as Eun-ju

Lee Jong-hyuk

as Cha Jong-hoon

Park Hyo-joon

as Ham Jae-bok

Seo Dong-won

as Seong-hun

Kim Dong-young

as Young Hyeon-su

Cho Jin-woong

as Yasaengma Gang Member

Lee Gyu-ho

as Yasaengma Gang Leader

Kim In-kwon

as Jiksae

Baek Bong-ki

as Cheetah

Ahn Nae-sang

as Teacher

Kim Beong-choun

as Choi Byeong-sam

Kwon Tae-won

as English Teacher

Cheon Ho-jin

as Hyeon-su's Father