Japan is such a hard market. They often will choose Japanese only products regardless of the competition. I say bravo M$. You can do nothing but try. Look at car manufacturers. Non Japanese car manufacturers have never been able to sell theirs cars in Japan. Japanese will never accept them.
In terms of skills and sales. Japan seems to buy the Japanese developed games, but Western devs have sold alot more ths gen. And to be honest have created the far better games.