you know, the weird thing is, if I load it in gens, it appears to be in us format, loading the us bios.
But I never experienced readboot to be wrong before, it was always giving me the correct country.
For instance, I had a version of sonic cd, it was in eur hacked to us, but readboot recognized it as eur, although gens was playing it as us. But if snatcher has never been released in Japan, it means that by some mistake of the company who released it, there's written japan instead of us. This doesn't have to do anything with the country code though, it's just a good way of detecting dirty country hacks that may have been made on the iso.