Like January, February is a good time for visiting Japan as the weather is usually sunny and dry and sightseeing spots are not crowded. The downside of a visit in winter are the relatively short days (sunset is around 5:30pm in Tokyo) and the vegetation's barren state.
Northern Japan and the Sea of Japan coast receive lots of snowfall. At the peak of winter, February tends to be the best time for winter sports and viewing winter sceneries, such as the drift ice off Hokkaido and the snow covered farm houses of Shirakawago.