Ratu was an Indonesian music duo from Jakarta, Indonesia, formed in 1999 with Maia Estianty, then the wife of musician Ahmad Dhani, on instruments and Pinkan Mambo on vocals. Ratu entered the Indonesian musical scene with their first album, "Bersama" (Together) (2003). After a short break caused by Mambo's departure in 2004, the group formed anew with Mulan Kwok as vocalist. This new line-up proved more successful, with their most successful songs – "Teman Tapi Mesra" (Friends with Benefits) and "Lelaki Buaya Darat" (Womanizer) – released in this period; both song titles later became common terms in the Indonesian vocabulary. The group's second studio album, "No. Satu" (Number One) (2006), sold 200,000 copies on the day of its release, a record for an album by an Indonesian female group. The group dissolved in 2007.
Ratu was the most successful female Indonesian music group of the 2000s. Aside from their music, they were known for their physical appearance and wide coverage in infotainment media. Through their choice in costumes, Ratu popularised Harajuku styles in Indonesia. Throughout their career, the band won numerous awards; they were the first musical act to twice be declared "Artist of the Year" and "Group/Duo Artist of The Year" at the MTV Ampuh music awards. This success inspired numerous other groups to follow in their tracks.