I'm somewhat new the Japanese Wrestling scene, can somebody fill me in???

[Aborted_Griffin]

What exactly is going on with Mutoh and All Japan/New Japan? I was under the impression that he left NJPW to join AJPW, but quickly returned to New Japan. And I also thought he returned the the Great Muta gimmick? Have I been greatly misinfromed??? And what's up with Vader, Stan Hansen ((did he really retire?)), 2 Cold Scorpio, and all the other American guys that were popular here 10 years ago that now wrestle in Japan? I fell like everything I now know is wrong...

[The Franceman]

Mutoh is still with AJPW. He just came to make a special appearence in NJPW.

Vader has legits problems (and injury), Hansen is retired and Scorpio is with Misawa's NOAH.