Sadness is the transformation of Bane Rock Ballad, Choi Jung Chul's Choi Jung Chul, who is known as the son of Namie, who is recognized as a vocalist, plays the rock ballad. Choi Jung Chul's So is a song that expresses the pain and love of a man with MBC drama net [Zero task Zero] OST. Choi Jung Chul's emotional and appealing vocals blend in with melancholy melodies and are more attractive. This is a song by Kim Sung-soo producer who produced the drama OST such as [I'm Sorry, I Love You], [Let's Go to School], [To Love Me].