He debuted as the vocalist of さくらん (Sakuran) in January 1994. After さくらん disbanded in 1996, Ishii joined the minor bands マドリガル (Madrigal, on vocals) and undertou (on synths).
In June 2000 Ishii joined the popular alternative rock band cali≠gari replacing the previous vocalist. In June 2003 cali≠gari went on activity pause and Ishii started a solo project called Goatbed, which went on activity pause in May 2008. After that Ishii had some minor projects mostly as producer until cali≠gari resumed activities in April 2009. In December 2010 Shuji founded a new band called XA-VAT.