Japanese animation studios do occasionally adapt from foreign source material but from what I've heard, this usually flies like a lead balloon with Japanese viewers. This doesn't stop the studios from trying, however. The latest attempt is a series of collaborations with Marvel, including Iron Man, which I recently finished, Wolverine, and X-Men.
I enjoyed Iron Man. The action was good but to be honest the story was quite weak. The series is almost completely episodic, not the usual on going plot that is the typical format of good anime. Don't get me wrong, there is a plot, but it really isn't very complicated. It's as if the Marvel team had written this for the Saturday morning cartoon market. I'm beginning to understand why these types of adaptations don't go over well in Japan.
Despite what I just said, the series is worth checking out, especially if you are a fan of Iron Man. That part won't disappoint.