Jung In-gi

Professor Kim Chang-seok

Kang In-han

Won Jae-gu

Yeom Ki-nam

Kim Myung-jae, Secretary General of the Blue House

Kang Myung-guk

Seo Ji Seong Dad

Seo Gook-hwan

Nam Suk-goo

Oh Jeong-nam, Shi-young's uncle and prison warden.

Da-da's father (Ep. 5)

Soo-yeon's father (eps. 1–2, 16)

Corporal Jang Woo-seob, Baebangdong-2 officer

Go Yi-seok

Cha Seung-ho

Kwak Sung

Jang Woo-sup

Joon-hyung's paternal uncle and foster father

Sa Jae-sung – detective

Ahn Young-il

Eun-soo's father

Ki Ho-sang, Ha-myung's father

Cha Do-hyeok, the police section chief. He was in fact, the true culprit of the "Gap Dong" serial murders. He was sentenced to death nearing the end of the series Hyun Woo as young Cha Do-hyeok

Kim Tae-sool

Kim Sung-joon

Han Young-man, Yi-soo's father.

Yang Taek-nam

Han Deuk-ki

Gu Young-mok - director of The Morning of Keijo.

Yang Chul-dong

Yang Chul-dong

Ra-im's father

Kim Hwan

A cinematographer