In addition to his musical career, Ishii has executed a number of different projects, including acting as the spatial coordinator for HEP Five, coordination producer for the "Suzuka 8-Hour Endurance Races", the producer of "The Forest Fairy's Ball" for Expo 2005, and recently the producer of "Ground Angel in Hiroshima", an event commemorating the 60th anniversary of the Hiroshima bombing.
Alongside his many artistic talents, Ishii has also produced two films, ACRI ~The Legend of Homo-Aquarellius (1996) and Kappa (1994).
Ishii's song "River" also was used as the second ending to the anime Mobile Suit Gundam Seed.
Tatsuya Ishii guest starred in the Canadian science fiction TV series Sanctuary; he briefly appears as the head of the Tokyo Sanctuary at the beginning of the Season 2 finale "Kali", which aired on SyFy on January 15, 2010.
His character, Onryuji, head of the Tokyo Sanctuary, returned in two subsequent episodes, in Seasons 3 and 4.