Windows Store Region Restricted?

I am living in Japan. I have Windows 8 RP on a Samsung Series 7 Slate. I have set my region Japan and my language to English and "Find Apps in my Preferred Language" selected. When I go to the Windows Store, there are easily less than 500 apps in it. I tried changing my region to U.S, and all it does is cause Japanese language apps, like the Nikkei or Asahi Shimbun, to disappear from the store. And all of the apps are free apps, no paid ones. I haven't seen any updates to Windows built-in apps either.

This is very unsettling. I never had this happen with Apple's App Store. Is Windows Store restriced by region? If so, how can one living outside of a given region (or on vacation and in another region/country) get the apps they want?

If there is something I can do to fix it, like enter a U.S Credit Card, please let me know.