I doubt it to. Maybe they think Natal will do well in Japan?
I know in Japan they got Samuari Spirits Zero (aka 3d Sam Shodown) and a few other exclusive games. But overall I don't foresee anymore JRPG exclusives on the 360 with the exception of possible Mistwalker ones (Lost Odyssey 2 and Blue Dragon 2).
It's just that simple.