Tokyo stocks fell 0.92 percent in opening trade Monday ahead of a closely watched two-day policy meeting by the Bank of Japan.
The benchmark Nikkei 225 index, which closed Friday at its best level since April 2010, lost 98.34 points to 10,814.96 in early trade.
"All eyes are on the Bank of Japan, which should come through to meet expectations for more easing and some kind of inflation target rhetoric," said SMBC Nikko Securities general manager of equities Hiroichi Nishi.
The central bank is widely expected to launch further easing and adopt an annual inflation target of two percent -- a key demand from the new government led by Prime Minister Shinzo Abe -- in a bid to beat the deflation that has haunted Japan's economy for years.
Speculation about the measures has weighed on Japan's currency, with the dollar buying 90.18 yen in Tokyo forex trade against 90.08 yen in New York late Friday.
The euro firmed to 120.11 yen from 119.96 yen while it was flat at $1.3317.
-- Dow Jones Newswires contributed to this article --