Riyu Kosaka, born 17 January 1985 in Yokohama, Kanagawa Prefecture, Japan, entered the music scene as a vocalist and lyricist. After being selected in Konami’s 2000 audition for the teen pop group BeForU, she released the single "True..." in 2001, which gained popularity within the DDR community and marked her first solo recording. In 2004, Riyu Kosaka issued her debut solo album begin, featuring a mix of original tracks and re‑recorded Bemani songs, followed by the compilation Sky Girls〜Opening Theme「Baby's Tears/Kosaka Riyu」&Original Sound Track〜 in 2006. Her second studio album, every struggle, launched in 2008 under a major label and incorporated her recent singles, including "Danzai no Hana: Guilty Sky" (2007) and "Dober Man". Throughout her career, Riyu Kosaka contributed theme songs to anime such as Mokke with "Kokoro no ato" and the film Kamen Rider The Next with "Platinum Smile". Riyu Kosaka’s work extended into video game soundtracks, notably the 2019 mobile game Seven's Code, and she performed at the 2010 Live5pb. concert. While BeForU disbanded in late 2008, Riyu Kosaka continued solo releases, with her 7th single "Saisyo no MELODY" issued in 2011.