ONE: High School Heroes

Lee Jeong-Ha

Kim Eui Gyeom

Kim Do-Wan

Kang Yoon Gi

Kim Sang-Ho

Kim Eui-gyeom's father

Kim Joo-Ryung

Kim Eui Gyeom's mother

Hyun-soo Shin

Kim Soo-Kyum

Kim Jong-goo

Kim Ui-Gyeom's grandfather

Sung-Kyun Im

Kim Seung-joom

Yuk Jun-seo

Lee Gwi Jae

Yoo Hee-je

Choi Kisoo

Shin Jun Seop

Nam Seung-sik

Hyuntae Lim

Choi Hong-il

Kim Mi-ra

Kim Ui-Gyeom's aunt