He had to have owned the car himself for 12 calendar months or longer...

He had to have lived in Japan for most of that 12 months

When he comes over to Australia he need to prove that he's not going back anytime soon ie rental/lease termination/sold house, closure of bank account, resignation/termination of employment confirmation, new bank account in Australia, new house/rental or lease agreement and employment, TFN etc etc even if you provide all of that they may ask for even more proof

With personal imports they are very thorough to make sure people don't abuse it

This stops people that just visit from bring in cars, and stops people from coming for a week to sell a car and doing the same thing next year etc etc