As a Canadian living in the "colder" part of Japan, I have to say that your not going to find anything close to the Canadian winter.
I'm from the prairies and I'm used to winter being ridiculously cold.
I currently live in Niigata prefecture, and have seen 2 winters here now. The winter is very mild. On the coldest days it might hit -5. Hokkaido, I hear is colder, a little closer to Canada.
However I would recommend re-thinking 'snow'. In Japan, it's not dealt with like it is in Canada. In Canada we clear our sidewalks and roads with shovels and we put down salt and gravel. Here in Niigata, at least, snow is removed by spraying water on it. And while this removes the snow, everything is flooded. And on the cold days it means that everything is a sheet of ice. This last winter we had about 6feet of snow. I dont recommend basing where you go in Japan on snow. Winter is terrible because everything is soaking wet and icy.