AOA is a South Korean girl group formed by FNC Entertainment. The original 2012 eight-member line-up included: Choa, Jimin, Yuna, Youkyung, Hyejeong, Mina, Seolhyun and Chanmi; the group is currently promoting as four. Youkyung left the group in 2016, while Choa left in 2017 due to mental health reasons, followed by Mina in 2019 to pursue her acting career, and Jimin in 2020 due to bullying allegations by Mina.AOA began their career simultaneously promoting as a dance group and band, and officially debuted in July 2012 with the release of the single album Angel's Story. In early 2013, the band unit AOA Black released their official single titled "MOYA" to moderate success. They released their first EP in June 2014, and that year they also debuted in Japan under Universal Music Japan. The group found nationwide success in 2014 after a series of hit songs that established them as one of the leading girl groups of their era. "Heart Attack" debuted at the top of several charts after its release, became one of the most downloaded songs of 2015, and became one of the longest charting singles on Melon's top 100 chart.