Hey there, I used to live in Japan, so maybe I can help. How far south will you be? South of Tokyo there is no snow that I can think of. North of it not too far there are mountains and some great places to ski. Hokkaido of course has loads of snow, but it is the furthest north. Flying within Japan is really expensive because there are only two airlines and they are both government subsidised so they collude. Expect to pay a lot for even a small flight. However, you can get around easily on the train which is really fast and efficient. The way to to this is to get a JR Rail Pass BEFORE you go to Japan. It works like the Eurail Pass in Europe where you buy it before you go, and then you can activate it and go on any trains in the country for a week (I think 2 week passes are available). I think each week is about $500 (less now with the exchange rate), which is substantially cheaper than the regular rates (My girlfriend got her money's worth in 1 day, taking the train from Sapporo to Tokyo). I went skiing in Hokkaido near Sapporo, Furano, and Obihiro. These were some of the biggest resorts in the country and they did not have terrain parks (a couple rails and maybe 2 jumps, but nothing we would call a park). PM me if you got any questions.