Young-ho doesn't have any dreams for his life. He has been studying for three years to enter a university. He decides to send a letter to his childhood friend So-yeon. But her younger sister So-hee receives the letter instead of her sick sister. So-hee writes back to Young-ho, pretending to be So-yeon. Meanwhile, So-hee takes care of her sick sister and also runs a secondhand bookstore with her mother.
| Directing | Cho Jin-mo | Director |
| Writing | Yu Seong-hyeob | Writer |
| Production | Hwang Keun-ha | Executive Producer |
| Production | Lee Jin-sung | Producer |
| Camera | Yoo Il-seung | Director of Photography |
| Lighting | Yoo Seok-moon | Lighting Director |
| Art | Kim Hyun-ok | Production Design |
| Art | Yeom Jin | Art Direction |
| Art | Jin Hoon | Props |
| Editing | Kim Sang-bum | Editor |
| Sound | Kim Jun-seok | Music |
| Sound | Gong Tae-won | Sound |
| Costume & Make-Up | Kim Jung-won | Costume Design |
| Costume & Make-Up | Lee Seo-jin | Makeup & Hair |
| Sound | Shon Yong-ik | Production Sound Mixer |
| Visual Effects | Kim Dae-jun | VFX Supervisor |
| Visual Effects | Yoon Dae-won | Special Effects Supervisor |
| Visual Effects | Kim Jung-min | VFX Supervisor |
| Visual Effects | Han Jae-ho | Visual Effects |
