Japan's most famous season is arguably spring when the cherry blossoms bloom and sprinkle parts of the country in pinks and whites. I visited the Japan in December and January, celebrating Christmas with sushi in Kyoto and New Year's Eve at a Buddhist temple in the heart of Tokyo. I'm biased, but I think Japan is its best in the winter months.
Scott Gold's January in Japan is 7 minutes of live-action proof of this. He captures some of Japan's most iconic destinations during the month of January, including Tsukiji Fish Market, Shibuya Crossing, the Tokyo Skytree, and Nijō Castle.