Yeah Niseko is in Hokkaido, which is the north island, approximately an hour's flight from tokyo, and then a few hours drive from Chitose airport near Sapporo. You can also take the train, but I'm not sure how long it takes.
If you're keen to stay on Honshu, the main island where Tokyo is, Hakuba is probably a good place to start, there are a ton of resorts around that area with varied sorts of riding available. Myoko Kogen has a good rep too, but again I haven't ridden there so can't speak for it directly. If convience and riding is what you're going for, just hang around Honshu, there are so many resorts around there.
Personally if i were going for 2 weeks, I'd hang out in tokyo for a few days, and spend a week staying in Asahikawa, rent a car, and ride that area in Hokkaido, but that might be a bit hard to do without a little local knowledge and language.
If you're keen to stay on Honshu, the main island where Tokyo is, Hakuba is probably a good place to start, there are a ton of resorts around that area with varied sorts of riding available. Myoko Kogen has a good rep too, but again I haven't ridden there so can't speak for it directly. If convience and riding is what you're going for, just hang around Honshu, there are so many resorts around there.
Personally if i were going for 2 weeks, I'd hang out in tokyo for a few days, and spend a week staying in Asahikawa, rent a car, and ride that area in Hokkaido, but that might be a bit hard to do without a little local knowledge and language.