Kim Soo-ro as Cheon Seong-geun

Park Bo-young as Han Song-i

Lee Chan-ho as Ok Gi-ho

Kim Hyeong-beom as Cha Seung-ryong

Kim Ki-bang as Meok-tong

Park Jin-Taek as Jin-gook

Kim Yeong-ok as Seong-geun's Mother

Ha Jung-woo as Doctor

Jang Hee-Su as Gi-ho's Mother

Lee Yong-i as Eun-sil's Mother

Lee Hyung-Kwon as Vice-principal

Gong Ho-seok as Teacher Choi

Lee Han-wi as Principal

Kim Sung-ryung as President Lee

Moon Chae-won as Lee Eun-sil

Lee Min-ho as Oh Sang-hoon

Baek Sung-hyun as Baek Jung-goo

Lee Eon-jeong as Chemistry Teacher

Kim Byeong-ok as Publishing Company President

Kim Won-jin as Referee

Ji Hye-in as Ji Yeon

Son Min-ji as Interview Student 3

Oh Soon-tae as Ja Ba Nom