She's on Duty

Kang No-young, boy at school, Jae-in's neighbour

Detective Cho

Detective Kang

Seung-Hee, daughter of mob boss

Bae Doo-Sang, mob boss of the Whacker gang

Ja-gyeong

Math Teacher (cameo)

Chun Jae-in, undercover cop

Jo Hye-ryung

Class teacher