"Exports have bottomed out but I doubt whether they will accelerate from now on due to growing uncertainty over the global economy," said Takeshi Minami, chief economist at Norinchukin Research Institute.  The MOF data showed exports to the United States rose 23.7 percent in the year to December, while those to China rose 4.3 percent.  Read MoreA busy week ahead for Japan, Asia's central banks  Shipments to Asia, which account for more than half of Japanese shipments, grew 11.0 percent year-on-year in December. EU-bound exports rose 6.8 percent.  Overall imports rose 1.9 percent on the year in December versus a 2.3 percent gain expected, as sharp falls in crude oil prices cut into the value of purchases. That helped trim a trade gap by 49.5 percent from a year ago to 660.7 billion yen ($5.62 billion), still marking a record 30-month run of deficits.  Cheap oil also compounds the challenge for the BOJ's aim of hitting its 2 percent inflation goal around the coming fiscal year from April, which analysts see as impossible to achieve.  Indeed, on Wednesday the BOJ sharply cut its inflation forecast, and Governor Haruhiko Kuroda conceded it may take longer than expected to hit the price target.  The yen has fallen sharply against the dollar although it has pulled back from recent lows. The dollar was at around 118 yen on Monday, off a 7-year high of above 120 yen hit last month, but still about 35 percent higher since Abe took office in late 2012.  Despite the yen's depreciation under Abenomics stimulus policies, exports have been slow to pick up as Japanese firms shifted production overseas, while others have sought to boost profits rather than export volume.
Japan's exports grew the most in a year in December, helped by a weak yen and pickup in overseas demand, an encouraging sign for the economy.