BOL4

Bolbbalgan4, also known as BOL4 or Blushing Youth, 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 first syllable of the Korean word sachungi "puberty" is pronounced the same as the Sino-Korean numeral four, and accordingly the group name is sometimes shortened to BOL4.
The duo went on a temporary hiatus due to Ahn's music classes requirements in the first half of 2018. Bolbbalgan4 signed with King Records and debuted in Japan on June 5, 2019, with the mini-album Red Planet.
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 as a solo act.

From Wikipedia (https://en.wikipedia.org/wiki/Bolbbalgan4) under Creative Commons Attribution CC-BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0/legalcode)