Ji-Myung Lee as Billy, Sung-Hoon Lee as Michael, Young-Joo Chung as Mrs. Wilkinson, Won-Hee Cho as Dad, Jae-Hyung Lim as Tony, Joo-Shil Lee as Grandma, Mun-Hee Lim as dead mum, Geon-Soo Ham as George, Hyun-Ji Shin as Billy's Older Self