Amber Josephine Liu, also known mononymously as Amber, is an American singer, rapper, and songwriter. She debuted as a member of the South Korean girl group f(x) in September 2009. In 2015, she became the first f(x) member to make a solo debut with the release of her first extended play Beautiful and has since released solo singles in Korean, English, and Mandarin.

Invincible Youth is a South Korean variety show which aired its first season on KBS2 from October 23, 2009 to December 24, 2010. Season 1 featured seven girls from K-pop idol groups wherein they experience how it is to live and survive in the Korean rural outdoors. It started its second season on November 12, 2011 featuring eight girls.