Campsite
The campsite is impressive! It doesn't have paid on-site staff and the shop, baths, etc. are paid for on trust. Volunteers come in to do some stuff around the place.
I'm camped on a mix of gravel and woodchip (the woodchip definitely helps!).
Having wandered up the hill a bit, there are lots more places you can pitch - it really is large! There's also an 'alpine' lodge with an onsen hot bath that's only 500 yen rather than 1000...but it's over 5 minutes walk uphill from where I've camped, so I'm not sure I'll use it.