I don't have numbers, and am too lazy to find them right now, but yes Arn, Apple does well in Japan. In fact, Apple's marketshare in Japan is significantly higher than it is in the USA. Ever since Jobs took over, Mac marketshare in the USA has been at or below 5%, but there have been times in Japan when they have cracked 10% in certain market segments, like laptops, for instance.
There have been multiple occasions where a particular Mac model has been the #1 individual computer model in Japan, as well.
If I recall correctly, iPods have over 50% marketshare in Japan for MP3 players (or, at least, had that at some point during 2002).
So, anyway, I think Japan is really the best choice for the first non-USA Apple store.
Besides, Apple needs to start playing up the transparent multi-language capability of OS X, as it is one of the number one advantages right now of the Mac platform...especially with respect to Japanese, Chinese and Korean.