Tokyo stocks opened 0.66 percent lower on Thursday after the previous day's year-best gain of 2.39 percent as investors waited for the outcome of a Bank of Japan policy meeting.
The Nikkei 225 index was down 67.29 points at 10,093.11 at the start after it chalked up the year's biggest gain to close above the 10,000 level for the first time in more than eight months Wednesday.
"Stocks will likely tread water as players await the Bank of Japan's next decision on monetary policy due today," said SMBC Nikko Securities general manager of equities Hiroichi Nishi.
Stocks had risen on the back of a weaker yen following a landslide win by the opposition Liberal Democratic Party (LDP) and its ally in Japan's national elections on Sunday.
The Bank of Japan (BoJ) is under scrutiny to see if its stance or rhetoric reflects an increase in pressure from the incoming coalition to further loosen monetary policy. The bank wraps up a two-day policy meeting later Thursday.
"Given the supermajority election wins, the BoJ would be very unwise to ignore the people's decision," an equity strategist at a foreign brokerage told Dow Jones Newswires.
The yen was at 84.30 yen in early Asian trade, compared with 84.39 yen in New York Wednesday afternoon.
The euro bought 111.45 yen and $1.3217 against 111.59 yen and $1.3226 in US trade.