JA is a fairly new association and despite many activators it has tons of peaks so it will take time. Hakuba resorts are pretty stricts when it comes to side-country within resort boundaries and you can loose your lift ticket. Access to the backcountry from the top of the resorts such as Happo, Goryu, Tsugaike is allowed unless conditions forces them to shut it. More and more resorts nowadays now require a that you file a form indicating where you want to go, your planned route, number of people in your party, experience, etc…This form is called Tozan Todoke.
Most of the SOTA peaks to the West of Hakuba will be very hard to access unless you have some very advanced winter mountaineering skills. Some peaks to the East and South will be easier. Sometimes low elevation peaks can be hard to access as well due to the necessary bushwhacking even in winter.
It normally snows and snows and snows and… Finding blue-bird days can be tough and breaking trail in waist-deep powder can seriously limit what you can access.
You may want to dial in over a few days what peaks you want to access versus your BC skills. Start with an easy one and get a feel for the conditions and go from there.
If you activate SSB, be ready for some frustration. You will not get the pile-ups you would get in the US or Europe. If you do CW then no problem.
Good luck and enjoy the japow!