It's a numbers game. While the PS3 has over a millon install base in Japan, the Xbox 360 doesn't. Heck, it doesn't even have half a million. With 400,000 Xbox 360s purchased in The Land of the Rising Sun, no wonder SEGA is having second thoughts about releasing Virtua Fighter 5 for the Xbox 360. Sure, it will still get its fall US/Euro release. Lead designer Tohru Murayama explains:
We haven't decided if we'll release Virtua Fighter 5 in Japan because of that. But if we [can only release the game]for the US or EU markets, we just hope Virtua Fighter 5 will be a key title which encourages people to buy Xbox 360s.
The 360 version will include online versus play as well as other features not in the PS3 one. Bad situation for Xbox Japan to have major third party publishers considering to fore go domestic releases. Those Japanese Xbox 360 owners are probably dying to play VF5! Lack of faith, that's for damn sure. No Japan Release? [Games Industry]