Mamamoo, sometimes stylized as MAMAMOO, is a South Korean girl group formed by Rainbow Bridge World (formerly WA Entertainment) in 2014. The group officially debuted on June 18, 2014 with the song "Mr. Ambiguous". Their debut was considered by some critics as one of the best K-pop debuts of 2014. They are recognized for their retro, jazz, and R&B concepts and strong vocal performances.
Apink is a South Korean girl group formed by Plan A Entertainment (formerly A Cube Entertainment) in 2011. The group consists of Park Cho-rong, Yoon Bo-mi, Jung Eun-ji, Son Na-eun, Kim Nam-joo and Oh Ha-young. Hong Yoo-kyung left the group in April 2013 to focus on her studies.