A friend of mine forwarded this article (Japanese) to me.
The main point is that the number of registered foreigners in Japan was down for the first time in 48 years last year. The overall reduction was only 1.4% but the number of Brazilians was down 14.4%. The number of Chinese was up by 3.8%. The article points out the obvious that it's a result of the crappy economy and especially the loss of jobs for Nikkei laborers.