BOL4

BOL4 (Korean: 볼빨간 사춘기; RR: Bolppalgan Sachungi), also known as Bolbbalgan4 or Blushing Youth (赤頬思春期, Akahō Shishunki), is a South Korean musical act formed by Shofar Music in 2016. They appeared on Superstar K6 in 2014 before signing a contract with their current agency. BOL4 was originally a duo consisting of Ahn Ji-young and Woo Ji-yoon. They debuted with the single "Fight Day" from the mini-album Red Ickle on April 22, 2016. The duo went on a temporary hiatus due to Ahn's music classes requirements in the first half of 2018. BOL4 signed with King Records and debuted in Japan on June 5, 2019, with the mini-album Red Planet (Japan Edition). On April 2, 2020, Shofar Music announced that Woo Ji-yoon had left the duo and that Ahn Ji-young will continue to promote as BOL4. In April 2025, BOL4 parted ways with their agency after 10 years of working with them.