As you know, Panda has not come to Japan (and China/Korea) yet. We, Japanese webmasters have experienced some big algo changes this year but they don't seem related to Panda. Personally, I guess Google is testing Panda to google.co.jp and I heard from Matt Cutts at a conference they would roll it out to Japan, too but didn't tell when. Some of us are looking forward to Panda coming to our country but some are afraid of it.
Apart from Panda, penalties are getting severer and severer recently in Japan, though not so sever as in the U.S. That is also our concern.