Ko Kyu-pil

Yoon Ji-hoo

A private investigator

Kyung-rae

Mart staff (cameo, episode 2)

Han Tae-ju

Park Dong-seop: a self-employed vampire who runs a snack bar in front of a high school.

Gong Ha-neul

Obom, informant hacker and criminal with a criminal record.

Gong Dae-chul, Head of the Special Division of the Jungam District Attorney's Office.

Joo Jun-pal, a solver of the Heungshinso who is called detective Zhull.

Ma Dong-cheol

Do Young-soo, a clerk at the office of a public lawyer.

Eunuch Hong Kim Gun as young Eunuch Hong

Go Pil

Oh Yo-han

Park Jin-kyoo, planning team leader.

Kim Jin-ho

Tak Jung-hoon

Oh Yo-han

Hong Chang-sik

Park Kwang-deok, husband of one of the victims of the B357 plane crash who owns a judo gym.

Police officer (ep. #3)

Jung Sung-joo

Han Se-gye (eps. 1, 2)

Lead Bodyguard of Myeongdong Capital (Ep. 1, 3)

Loan shark

Jung Ja-wang – nickname "Keyboard"

Chinese restaurant's deliveryman

Yoo Myung-hyun

Dan-bi's math teacher / Head Eunuch

(ep 13)

Jang Myung-kil – Hyeonjong's eunuch.

Jang Dong-gun

Young Chang-joo

Hyuk-joon's co-worker

Yun Bok