When Gundam Musou was released back in March it didn’t get a dual platform release like North America. It was only a Playstation 3 game in Japan. During a chat I had with Namco Bandai I asked if they were going to release the Xbox 360 version in Japan and months ago they weren’t sure.
Enter Gundam Musou: International. Namco Bandai announced that the Xbox 360 version will come to Japan with English and Japanese voice acting on the same disc for 7,800 yen ($66). Besides the extra language track and the required achievement points, there aren’t any other differences compared to the Playstation 3 version. It also looks like there isn’t going to be any bonus content for Japan only either unlike other International versions, so you’re not missing out on anything special unless you want Japanese menus.