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

Lee Jun-hyeok

Policeman

Seo Dong-soo

Army Colonel (uncredited)

Jung In-gum

(uncredited)

Koo Kyo-hwan

Drunk Man (uncredited)

Kim Eun-sook

Military Chief (uncredited)

Lee Min-woong

Dr. Kang's Assistant (uncredited)

Nam Jung-hee

Dong-suk's Grandmother (uncredited)

Ahn Do-gyu

Dong-suk (uncredited)

Kim Jong-goo

Sun-yi's Father (uncredited)