Sweetheart, if youre going to do this, you should tell him about the trip.
Itll be fun to organize the trip together plus you can slash away a heap of stress getting things organized.
If you are looking to do something outside of the normal "travel tour" route, youll need him to help you sort things out before you get here.
Remember, Niseko is not the be all and end all of skiing in Japan. Last year we had some of the powder of the season in Nagano which is a couple of hours by Shinkansen from Tokyo. Thigh deep and blue skies.
You will be able to source accomodation easily - i know many locals up there and can help you out with some very nice lodging for $40 a night, breakfast included..for example. Lift passes for happo and hakuba are around $35 for the day which is peanuts when you think about it.
Try not to get stuck on the "tour Japan to find the cars" thing because to be honest, youll be selling yourself short.
Trust me. His mates may go "Phwoargh" when he says how sick the autosalon was but i guarantee he'll remember you and the experience more if you did something a little more...closer to the heart. Temples and shrines are a good place to start, for example.
But if youve made the choice, who am i to deny you.
Two things - get a lonely planet guide.
And buy the Japan Rail pass.
Dont come here without one.
Drop me a line if you need some more advice.