Hi Jex,
Well there is some great snow in Japan - depends on what you want to do. If you fancy taking in Tokyo as well then I would say try Niigate or Nagano - my favorite is Nagano. If you don't mind where you are in Japan then you could try Hokkaido - the powder snow is supposed to be the best here.
I've added a great link below for you - they have up to date info. Hope it helps
http://www.snowjapan.com/e/index.php