Moumoon (stylized as moumoon) is a Japanese pop duo consisting of two members, vocalist and lyricist Yuka and composer Kōsuke Masaki. Formed in 2005, the duo signed with Gate Records in 2006, and released their debut single "Flowers/Pride", and mini-albumFlowers that September. In 2007, they left Gate Records and signed with Avex Trax, releasing their second mini-album, Love Me? in August. The duo's name is a combination of the French "Mou" and the English "Moon", together meaning "Soft Moon".
Yuka and Masaki met in the summer of 2004; however, it wasn't until 2005 that they formed Moumoon. In October 2005, the duo held their first live performance at the Omotesando FAB. In 2006, they signed with the indie label Gate Records and released their debut single "Flowers/Pride". The single charted on the Oricon single charts at number 106. Soon after, Moumoon released their debut mini-album, Flowers (September 2006), which debuted at number 63 on the Oricon album charts.
On May 12, 2010, they released their eighth single, "Sunshine Girl", which entered the Oricon single charts at number 12, a first for the group. The following week the single rose to number 10, becoming their first Top 10 single. The duo released their fourth mini-album, titled Spark, on July 7, 2010.