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

Myeong Da-bin

Hyun-soo Shin

Kim Soo-Kyum

Kim Jong-goo

Kim Ui-Gyeom's grandfather

Yuk Jun-seo

Lee Gwi Jae

Sung-Kyun Im

Kim Seung-joom

Yoo Hee-je

Choi Kisoo

Hyuntae Lim

Choi Hong-il

Kim Mi-ra

Kim Ui-Gyeom's aunt

Shin Jun Seop

Nam Seung-sik

Bae Gi Beom

Tailor Moon

Dong-hyeon Kim

Dr. Kim