And an IP issue on top of that in Japan. Xbox simply doesn't have many games that Japanese players want to play. Unless Microsoft wants to make Minecraft an Xbox exclusive, they'll need to get a lot of Japanese games onto their console, and many of them exclusive to their console.
That didn't work last time they tried it on the 360. Almost every Japanese developer that got in bed with Microsoft for exclusivity ended up regretting it badly. US sales didn't make up for lost Japanese sales. Namco used the money Microsoft paid them for 360 games like Eternal Sonata and Tales of Vesperia to make better versions for PS3 to try and make up what they lost in sales by being 360 exclusive. Vesperia did so poorly on 360 that the Tales studio got shut down.
Microsoft honestly needs to face the facts about the Xbox in Japan. It's never going to happen. They need to content themselves with the handful of multinational-focused Japanese developers willing to port their popular-in-the-US games and focus on the Western market otherwise. Other than that, they need to leave Japanese games to Nintendo and Sony.