Song Joong-ki
Wolf-Boy / Chul-soo
Park Bo-young
Young Sun-yi / Eun-ju
Yoo Yeon-seok
Ji-tae
Lee Young-lan
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)
Jung In-gum
(uncredited)
Lee In-ho
(uncredited)
Oh 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)