Renting snowshoe&stock cost 1000JPY/person
Private tour cost from 3000JPY-(per person)
*for the tour costs, available course, dates and so on... please ask directly to the organiser.
If you have no own vehicle access, better to ask a meeting point where you can reach by public transportation.
The tour is organised by Onikko-no-kai(鬼っこの会)
Their official blog.(in Japanese)
If you are interested, please ask your accommodation or Japanese person to assist you to make a reservation due to the organiser can't speak English, I think.
For booking, call 090-3466-4376(from Japanese domestic phone), +81-90-3466-4376(from foreign phone).