Tokyo stocks opened 0.65 percent lower Wednesday after the dollar fell against the yen, despite a deal reached by Congressional negotiators on US spending that aims to avoid a repeat of the government shutdown which paralysed Washington.
The benchmark Nikkei 225 index lost 101.38 points to 15,509.93 at the start.
Under a deal reached in October that ended a crippling 16-day shutdown, federal spending authority expires on January 15, when a new agreement will need to be in force.
The two-year agreement reached on Tuesday sets the warring Democratic and Republican Parties on track for further cooperation on fiscal policy, ending the cycle of budget feuding that has marred Washington since 2011.
The challenge now is selling the agreement to sceptical conservatives and liberals in the Senate and House of Representatives.
US stocks Tuesday ended lower as investors looked ahead to a retail sales report that covers the beginning of the critical holiday shopping season.
The Dow Jones Industrial Average fell 0.33 percent to 15,973.13.
The US dollar fell again Tuesday as expectations for significantly tighter monetary conditions from the Federal Reserve dissipated on hints of only a slight taper of its stimulus.
The dollar fetched 102.84 yen early Wednesday, hardly changed from 102.81 yen in New York Tuesday afternoon but down from 103.30 yen in Tokyo on Tuesday.
A stronger yen is bad for Japanese exporters as it makes them less competitive abroad and erodes repatriated profits.
The euro bought $1.3761 and 141.60 yen, almost flat from $1.3760 and 141.68 yen in US trade.