"4 Walls" is a song recorded by South Korean girl group f for their fourth studio album of the same title. The song was written by Jam Factory's Lee Seu-ran, whilst the music was composed by LDN Noise

Chrystal Soo Jung, professionally known as Krystal Jung, is an American and South Korean singer and actress. She debuted in 2009 as a member of the South Korean girl group f and has further participat