Featured KNK (크나큰) KOREAN KNK (크나큰) – KNOCK KNOCK “Knock” [Single] KNOCK 2016.03.03 Youjin, Seungjun, Inseong, Jihun, Heejun Lyrics/작사: ButterFly Composer/작곡: ButterFly Arranger/편곡: ButterFly