Chul-soo is a man with an intellectual disability. One day, Chul-soo finds out that a young girl, Saet-byul, who is in hospital is his daughter. And soon, Saet-byul sneaks out of the hospital and travels by herself to a faraway city for her friend's birthday. As Chul-soo accompanies Saet-byul's journey, friendship develops between the two.
Unfortunately the movie Cheer Up, Mr. Lee is not yet available on HBO Max.
| Art | Kim Hyung-jik | Set Decoration |
| Production | Park Ji-young | Executive Producer |
| Production | Jay Lee | Executive Producer |
| Writing | Bang Woo-ri | Adaptation |
| Editing | Ryu Yeon | Digital Intermediate Producer |
| Sound | Park Hyun-soo | Production Sound Mixer |
| Sound | Bang Jun-seok | Original Music Composer |
| Writing | Park Jeong-ye | Adaptation |
| Writing | Noh Kyung-hee | Adaptation |
| Production | Park Ji-sung | Executive Producer |
| Art | Park Yong-gyu | Props |
| Writing | Lee Kae-byeok | Writer |
| Writing | Jang Yoon-mi | Writer |
| Directing | Lee Kae-byeok | Director |
| Writing | Kim Hee-jin | Writer |
| Production | Kim Jeong-bok | Producer |
| Production | Syd Lim | Executive Producer |
| Camera | Kim Jeong-won | Director of Photography |
| Art | Lee Na-gyeom | Production Design |
| Editing | Yang Jin-mo | Editor |
| Lighting | Jung Hae-ji | Lighting Director |
| Costume & Make-Up | An Ji-hyeon | Costume Design |
| Costume & Make-Up | Park Yea-ri | Makeup & Hair |
| Production | Kim Yong-hwa | Co-Executive Producer |
| Costume & Make-Up | Pi Dae-seong | Special Effects Makeup Artist |
