Looks like you have a sweet place set up there. I live in Kyoto. Been here for 10 years but I'm a Brit too.
What are your stats and your boards?
Unless you have some big twin boards you might struggle a little in the BC around there. Even on piste after and during a big dump you might want a more directional board. You can always borrow a board from a local shop for the day when it gets super deep. They are pretty chill about it and if you become friends they will hook you up regardless of if you have any interest in buying the board.
If you want to do lots of powder riding it might be worth getting a deck before you go as they are twice the price in Japan.
I hope you find someone to go halves with you but if not there are quite a lot of people who come on this site looking for a place to stay for a week or two in Niskeo. 3 or 4 thousand per person per night would be a good deal for both of you.
Of course you might want to make sure they are not party animals and destroy your house.
Enjoy the Hokkaido winter.