Thursday was not a holiday in Japan. My American firm did not give us the day off, but they did cater a lunch that included turkey, mashed potatoes, gravy, stuffing, and little pumpkin pie squares. It was nice of the firm to do this... I was missing my family and our traditional Thanksgiving a lot that day.
Friday was a Labor Day holiday in Japan so our office was closed. One of the associates coordinated a pot luck for the unmarried associates. He made the turkey--which was great because turkey can be hard to find and many of the ovens, if you even have one, aren't large enough to cook a turkey. I broke in my kitchen by cooking up some creamed corn (the real adventure was in shopping for the ingredients). Dinner was tasty and it was nice to have company.
I heard from a kiwi that I met in Japanese class that the Japanese expect all white people to celebrate Thanksgiving even though it's really just an American and Canadian holiday. He seemed a bit put off that his Japanese friends were continually asking him what he would be doing for Thanksgiving. So, there is an awareness of Thanksgiving here, but I didn't see any decorations or explicit acknowledgement of it.