Who is the vocalist in Kim Wu's theme?

Characters Kim Wu
1

In the behind the scenes of Kim Wu’s theme, Rami Seo did the gayageum, but who was the vocalist?

I’ve been asking and nobody knows.

2

The VERY same person that you just mentioned singing in Kim Wu’s new theme: Rami Seo

3

Forget it. U guys were slow. The vocalist’s is Hoona Kim.