That compared with a 1.9 percent decrease expected by economists in a Reuters poll. It followed a 0.1 percent rise in November.
Imports rose 1.9 percent in the year to December versus the median estimate for a 3.7 percent increase.
The trade balance came to a deficit of 55.3 billion yen ($505.81 million), versus the median estimate for a 29.5 billion yen deficit.
(Reporting by Tetsushi Kajimoto; Editing by Chang-Ran Kim)