I’ve been watching Oh My Ghost and the ghost character sings the chorus of a song over and over. It’s really pretty and I searched for it. What I found out is that it’s an old Latvia song (1981) that was translated in Korean in 1997. It was originally sung by Sim Soo Bong, and the lyrics were changed, talking about a love to an alien that is on Earth and wants to go back or something (My Love From The Stars much). I’ll put a few version of it here since it was redone a few then since 1997. It’s called One Million Roses.
Here is the original
Here is Chang Kiha singing it with Sim Soo Bong in a more modern version of it
Here is Davichi singing a shorter version of it
Sadly, I didn’t find any video of how it’s sing in the drama (mainly the chorus a cappella). It’s stuck in my head forever.