4K is a South Korean four-member acoustic boyband. Comprised of 4 male members (Cory, Seok-June, Sung-Oh, and Ki-Su).

4K officially debuted on June 12, 2012, releasing their first single "Rocking Girl". Four unique yet harmonizing voices come together to re-define K-pop by defying its typical electronic music with lyrical acoustic tunes.

4K's album comprises of three songs "Rocking Girl" , "Bye Bye Bye", and "Moonlight Sonata" as story- telling artwork of love.