Japan has a very rich culture and one of the most visited countries in the world. You can go there anytime of the year, but if you’re planning to go there during the winter you can check this article about winter adventures.
Japan is situated in northeastern Asia between the North Pacific and the Sea of Japan. The area of Japan is 377,873 square kilometers, nearly equivalent to Germany and Switzerland combined or slightly smaller than California. Japan consists of four major islands, surrounded by more than 4,000 smaller islands. (source)
You can also check this video for a taste of Tokyo during winter: