Shin Hye-sun as So Si-min

Lee Jun-young as Han Su-gang

Park Jung-woo as Ko Jin-hyoung

Park Hyeok-kwon as So Young-taek

Cha Chung-hwa as Lee Jae-gyeong

Lee Chan-hyeong as Lee Gwon-joong

Bae Hyeon-jun as Byeong-jin

Cha Woo-min as Lee Moon-gi

Kim Sang-woo as Park Jung-ho

Lee Tae-hee as Kim Jeong-gyu

Lee Tae-gyun as Byun Jae-hyeok

Kang Anna as Song Eun-gyo

Kang Na-ru as Min-ji

Son Sook as Jin-hyoung's Grandmother

Lee Gyu-hoe as Head Teacher

Lee Jung-ok as Seo Sang-woo

Dong Hyo-hee as English Teacher

Nam Jeong-woo as Math Teacher

Kim Gyeong-ryong as Principal

Lee Do-eun as Hye-gyeong