Since the two airlines are both *Alliance, I would not expect there to be any problem at all to check luggage through. I have not checked luggage on these two particular airlines, but I have checked luggage on two tickets frequently. And, as the previous poster has said, Air New Zealand is in Terminal 2, while ANA is now in Terminal 1.

It is really no big deal to transfer between terminals - they have an airside bus that runs about every ten minutes or so. I think I would have had a tough time finding the bus on my own, but at Narita, everyone is so helpful that you will just ask anyone and they will direct you to the bus.

Have a terrific trip!