The film is a heist comedy set in 1940s Korea, and stars Park Yong-woo and Lee Bo-young as a con artist and jazz singer who each plot to steal a valuable diamond from the Japanese authorities.
Unfortunately the movie Once Upon a Time is not yet available on HBO Max.
| Directing | Jeong Yong-ki | Director |
| Visual Effects | Kim Byeong-gi | Special Effects Supervisor |
| Writing | Jeong Yong-ki | Adaptation |
| Sound | Kim Woo-chul | Original Music Composer |
| Costume & Make-Up | Hwang Hyun-gyu | Makeup & Hair |
| Production | Yoon Hong-jun | Production Manager |
| Production | Im Yeong-ho | Executive Producer |
| Writing | Chun Sung-il | Writer |
