An anonymous love letter addressed to P5 student Lam Siu-wai throws her and her classmate So Hoi-shing into turmoil. The duo decides to find out who wrote the letter. Thus begins a journey whereby the two kids get their first taste of many things unknown to them.
| Actor | Role |
|---|---|
| CChan Siu WaiSiu Wai / Lam Siu Wai | Siu Wai / Lam Siu Wai |
| LLo Ka OnShing / So Hoi Shing | Shing / So Hoi Shing |
| JJustin Wong Kei MinEdward Tai / Tai Tak Wah | Edward Tai / Tai Tak Wah |