Song Joong-ki

Wolf-Boy / Chul-soo

Park Bo-young

Young Sun-yi / Eun-ju

Yoo Yeon-seok

Ji-tae

Lee Young-ran

Sun-yi

Jang Young-nam

Sun-yi's Mother

Kim Hyang-gi

Sun-ja

Yoo Seung-mok

Professor Kang Tae-shik

Shin Bi

Dong-mi

Woo Jung-kook

Mr. Jung

Goo Bon-im

Mrs. Jung

Lee Jun-hyeok

Policeman

Soel Oh-shin

Thug 1 (uncredited)

Han Min-hik

Thug 2 (uncredited)

Chuay Kwong-lak

Thug 3 (uncredited)

Sung Du-hyung

Man in Black Suit 1 (uncredited)

Cha Jong-ho

Man in Black Suit 2 (uncredited)

Seo Dong-soo

Army Colonel (uncredited)

Jung In-gum

(uncredited)

Lee In-ho

(uncredited)

O Yeong-seok

Policeman 2 (uncredited)

Ku Lu-han

(uncredited)

Kim Chul-jun

Construction Worker at Market 1 (uncredited)

Park Young-shik

Construction Worker at Market 2 (uncredited)

Kim Seung-hun

Public Official (uncredited)

Koo Kyo-hwan

Drunk Man (uncredited)

Kim Eun-sook

Military Chief (uncredited)

Hong Sung-ki

Acupuncturist (uncredited)

Hung Hi-kwon

Hospital Doctor (uncredited)

Lee Min-woong

Dr. Kang's Assistant (uncredited)

Nam Jung-hee

Dong-suk's Grandmother (uncredited)

Ahn Do-gyu

Dong-suk (uncredited)

Kim Hae-eun

Woman Renting Mr. Jung's Room (uncredited)

Lee Sung-ju

Sun-yi's Son (uncredited)

Jang seo-yi

Sun-yi's Daughter-in-Law (uncredited)

Jo Jae-yun

Sun-yi's Grandson (uncredited)

Kim Jong-goo

Sun-yi's Father (uncredited)

Shin Yeong-cheol

Eun-ju's Boyfriend (uncredited)

Seol Woo-sin

Gangster 1