is a Japanese pop singer and lyricist. She is best known as a member of the Konami-produced Japanese teen pop girl group BeForU. Biography Early life Kosaka was born in Yokohama, Kanagawa Prefecture, Japan on January 17, 1985. Career Discovery by Konami On November 20, 2000, Konami and Toshiba-EMI staff held auditions to form a J-pop group, which would eventually become BeForU; Riyu, who was then fifteen years old, was one of four who went on to join the group. The group, produced by Naoki Maeda, originally made songs specifically for Bemani games—their first song, Dive, was promoted intensely in the time leading up to the release of Dance Dance Revolution 5thMix. True... After Dive's success in 5thMix, BeForU produced more tracks for inclusion in DDRMAX Dance Dance Revolution 6thMix, including Dive: More Deep and Deeper Style and Firefly. This is where Kosaka got her first solo track, True.... Two different versions were included in the game, True... (radio edit) and True...: Trance Sunrise Mix. For the first time for any member of BeForU, a CD single was released. including a long version of both the radio edit and the trance sunrise mix, as well as a remix of a solo performance of Dive, renamed Dive to the Night. True... was a success in the DDR community, and Kosaka continued to release other songs for use in Bemani both with BeForU and as a solo singer. Breaking out from Bemani While they continued to make music for Konami, BeForU began to put more emphasis on themselves as legitimate musicians, and this included Kosaka. In 2004, the band's first CD was released, containing some solo work by Kosaka; in the same year, her first full solo album, Begin, was released. Begin contained three original songs, as well as eleven re-recorded Bemani songs, some of which were covers of other artists. A year later, she released Riyu Kosaka First Live at O-EAST 2005, a CD+DVD set of her first full-blown concert. (This cannot actually be considered her first live performance, as she did limited performances to promote her single True.... ) Since that time, Kosaka has released a number of singles both on her own and with BeForU, as well as a new album with BeForU. In 2005 and 2006, she also collaborated with Ryo Horikawa as a radio personality for Pakedio Channel, and her song Little Wings is available on the