I actually don't think he ever said.
Supposedly, Toyama Ryu was his original art and perhaps what "Goshindo" is based on. I never saw the Goshindo.
He does have a video series that is quite obviously based on Toyama Ryu. Althuogh it is not the Toyama Ryu that we do.
All any offical bios I read just say "trained in Japan", "trained in Yokohama" or phrases like "certified in Japan".