The Hokkaido Government has begun taking radiation readings in Hirafu Village, in front of the Welcome Center by the Alpen Hotel. The Japanese government says the acceptable national limit is 3.8μSv/h, and radiation levels taken in Hirafu Village show levels of under 0.05μSv/h. This tiny amount is actually lower than residual radiation levels in many major overseas urban centers.
You can see monthly updates on the radiation levels on the Hokkaido Government website, which shows tourism areas around Hokkaido. Hirafu Village in Niseko is listed the third from the top, and the radiation reading for October is 0.036μSv/h:
360Niseko has been doing their own independent radiation readings in Niseko, and you can read them here:
Daily readings from Kutchan Town are available as well:
Part of the reason to publicize these readings was to address a great concerns from overseas tourists. With handheld radiation readers easily available, it is also easy to confirm these readings. With these low radiation levels, hopefully anyone planning a trip to Niseko will feel at ease.