The 360 is braindead in Japan. MGS4's first week sales will probably crush the 360's best selling game's LTD for Japan, Blue Dragon. And Blue Dragon has outdone the second best selling 360 game for Japan by about 2 to 1.
IMO high end ambitious Japanese targeted content on the PS3 and lowend demanding content targeted at PS2 and Wii makes much more sense, rather than wasting Japanese talent on creating 360 games for Japan.