Kim Jae Hwan is the voice behind "Black Sky" for the 'Chief of Staff' OST.

"Black Sky" is part 2 of the OST, and it's a melodic ballad song about hidden emotions that serves as the theme song for Jang Tae Joon (played by Lee Jung Jae) and other political players in the drama series. It's also Kim Jae Hwan's first release since his debut song "Begin Again" this past May.

Check out Kim Jae Hwan's "Black Sky" above!