I too was under the impresseion that objects marked "Japan" or
"Made in Japan" post-date WWII. In fact, at least one source dates them
from the 1950's, but I'm afraid I don't have that to hand, so I'll have to
search around at work tomorrow. I thought that Japanese wares from between
the McKinley Tariff Act (1891) and WWII were marked "Nippon" - at least in
the United States.
Alasdair M. Brooks