In this endearing supernatural love story spanning two decades, a university student finds himself communicating with a female classmate from the same school through an antique ham radio.
| Actor | Role |
|---|---|
 Kim Ha-neulYoon So-eun | Yoon So-eun |
 Yoo Ji-taeJi-in | Ji-in |
 Ha Ji-wonSoe Hyeon-ji | Soe Hyeon-ji |
 Park Yong-wooJi Dong-hee | Ji Dong-hee |
 Kim Min-jooHur Sun-mi | Hur Sun-mi |
 Shin Cheol-jinSecurity Guard | Security Guard |
| YYoo Tae-gyunYoon So-eun's Father | Yoon So-eun's Father |
| LLee In-okYoon So-eun's Mother | Yoon So-eun's Mother |
| LLee Yeong-gwangProfessor | Professor |
 Kim Sang-wonJi-in's Friend | Ji-in's Friend |
| KKong Yu-seokJi-in's Friend | Ji-in's Friend |
| YYoo Jin-heeHospital lady | Hospital lady |
 Maeng Bong-hakDoctor | Doctor |
| KKim Do-sikButler | Butler |
 Kim Bang-sunLibrarian | Librarian |
| KKim Do-yoonHam Radio Club 1 | Ham Radio Club 1 |
 Son Kang-gookHam Radio Club 2 | Ham Radio Club 2 |
| LLee Kyung-hoonLiterature Club 3 | Literature Club 3 |
 Lee Seung-chanLiterature Club 4 | Literature Club 4 |