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.