Roots of IU

Son Ga-in, known mononymously as Gain, is a South Korean singer, actress and entertainer, best known as a member of the South Korean girl group Brown Eyed Girls. Having debuted with her home group earlier in 2006, Gain eventually made her solo debut in October 2010 with Step 2/4 to great commercial success, and has since released a total of six extended plays. In addition to her musical career, the singer also appeared in several native programs and series, most notably We Got Married and All My Love for You, where she co-starred alongside 2AM's Jo Kwon.

Choi Jin-ri, known professionally as Sulli, was a South Korean singer and actress. She first made her debut as a child actress, appearing as a supporting cast member on the SBS historical drama Ballad of Seodong (2005). Following this, she earned a number of guest roles, appearing in the television series Love Needs a Miracle (2005) and Drama City (2007), and the film Vacation (2006). She then subsequently appeared in the independent films Punch Lady (2007) and BA:BO (2008), the former being her first time cast in a substantial dramatic role.

Lee Gi-kwang, known professionally as Gikwang or Kikwang, is a South Korean singer, songwriter and actor. He originally debuted as solo singer with the stage name AJ, releasing his first mini album First Episode: A New Hero on April 4, 2009. In October 2009, he debuted as the main dancer, visual and a lead vocalist of boy group Beast, which was renamed Highlight in February 2017.