On a live music radio show, a letter arrives from the 23 years in the past. Through the letter, the first love and friendships of five friends are revealed.
Unfortunately the movie Unforgettable is not yet available on Disney Plus.
| Visual Effects | Kim Han-joon | VFX Supervisor |
| Writing | Han Chang-Hoon | Screenplay |
| Writing | Lee Eun-hee | Screenplay |
| Directing | Lee Eun-hee | Director |
| Sound | Kim Sin-yong | Production Sound Mixer |
| Camera | Ji Sung-yong | Key Grip |
| Production | Choi Ki-sup | Producer |
| Editing | Kim Hyung-joo | Editor |
| Production | Jeong Mun-gu | Producer |
| Production | Joo Pil-ho | Producer |
| Camera | Lee Joon-gyoo | Director of Photography |
| Production | Bang Mi-Jung | Producer |
| Sound | Lee Ji-soo | Original Music Composer |
| Costume & Make-Up | Lee Jin-suk | Costume Design |
| Art | Lee Hyun-joo | Production Design |
| Writing | Kim Jin-a | Adaptation |
| Writing | Hong Chang-pyo | Adaptation |
| Lighting | Song Jae-wan | Lighting Director |
| Visual Effects | Park Choul-yong | Special Effects Supervisor |
