Moumoon (stylized as moumoon) is a Japanese pop duo comprising YUKA (vocals) and Kousuke Masaki (guitar). The band's name is a portmanteau of the French word "mou" (soft) and the English "moon".
The duo met at a summer rock festival in 2004; after swapping demo tapes, the pair decided to work together professionally. The band self-produced and arrange the vast majority of their songs, with Masaki composing the music while YUKA writes the lyrics.
Both band members were brought up on classical music, with Masaki playing piano and YUKA a keen violinist. Their present musical style covers various types of music such as pop, alternative rock, electronica, folk and indie rock.
A popular band in their native Japan and elsewhere, many of their songs have received massive amounts of radio airplay, and been used in TV commercials and television soundtracks. They tour regularly (including a sequence of "Fullmoon Live" shows every full moon night), and are best known for their 2010 top-ten single, "Sunshine Girl".