東京都交響楽団
Iwashiro has composed the music for many Japanese television series and films. He has composed for both "Red Cliff" films, ', "Azumi", "The Prince of Tennis", ', and the Korean film "Memories of Murder". He was also lead composer for the Capcom video game "". Iwashiro has often led the Tokyo Metropolitan Symphony Orchestra for his soundtracks, including the 2005 taiga drama "Yoshitsune" and 2008 film "Red Cliff".