BOL4

Bolbbalgan4 (, also known as BOL4 or Blushing Youth) is a South Korean duo 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 meaning of 사춘기(思春期) is "puberty" in English. In Korean, the pronunciation of 사(思) is the same as 사(四=4), so the group name is sometimes shortened to Bol4. On April 2, 2020, Shofar Music announced that Woo Ji-yoon had left the duo, and Ahn Ji-young will continue to promote as Bolbbalgan4.

BOL4 consists of members Ahn Ji-young and Woo Ji-yoon. Both of them were classmates and been dreaming as a singer. Then, they appeared on Superstar K6 in 2014 which lead them signing with Shofar Music. They debuted in 2016 with the single "Fight Day" and becomes success with their dreamy concept.