The second bout of heavy selling in Japanese stocks in as many weeks is not just about a strengthening yen and pulling-back from lofty levels, traders say.
There's also nervousness that upcoming U.S. data could signal an early unwinding of the Federal Reserve's asset-buying program.
The Nikkei closed Asia trade down more than 5 percent at 13,555,its lowest level in a month. It has fallen just over 15 percent from a 5-1/2 year high set last Thursday, just before the Nikkei went on wild swing later in the day to plunge more than 7 percent after weak Chinese data sparked a bout of profit taking.
"We are all looking at the Nikkei right now and this 5 percent drop is a shock," said Desmond Chua, a markets analyst at CMC Markets in Singapore.