Original source: Ariang Showbiz Korea
Part of the band “Transfixion” talking about JKS starts from 3:14min to 4:20min
The following the video JKS plays and sings the song in the movie “Happy Life”. It was just like they talked about him in the previous video. He did great to portray main vocal of a rock band in “Happy Life”
This video is when he sang the OST in a award ceremony.