Soichiro is famous for his role in Sonic X as Sam Speed.
He is part of the voice-acting company Office Osawa.
Notable voice roles
- Cyborg 009 (young Dr. Gamo Whisky)
- Daphne in the Brilliant Blue (Shibasaki Run)
- Devil Lady (Tawada)
- Glass Fleet: La legende du vent de l'univers (John Fall)
- Heat Guy J (Gena)
- Musashi Gundoh (Priest Takuan)
- Panyo Panyo Di Gi Charat (Uncle)
- Rave Master (Belial, La Grace, Tanchimo)
- Rockman EXE (Shuuseki Ijuin, CosmoMan, FreezeMan)
- Saiyuki (Ryokusho)
- Samurai Deeper Kyo (Haira)
- Sonic X (Sam Speed)
- Souichirou TANAKA, Anime News Network.