The Nikkei closes -0.6% to round off its worst month since May 2012, with the index dropping 8.5% in January.
Stock markets seem to be still highly troubled by the concept of positive economic news. In the U.S., the economy is trundling along nicely, while in Japan, inflation is heading towards the BOJ's 2% target and unemployment has hit a 16-year low. But it means that the Fed is tapering and the BOJ is less likely to add to its already massive stimulus.
Much of Asia is closed today, due to the start of the Lunar New Year, which will keep Chinese markets shut until February 6.
Of those bourses that are open, India is -0.1%.