Why not try to get it shipped from Japan -sort of does not make sense to ship from Japan to California just to ship it back west to Hawaii. You should not have any problems registering a shipped car as it should be no different than registering a car bought in one stated but titled in another. Most states will issue a 10 day (or there abouts) temporary in-transit tag and you would not pay any sales tax in that state either - just in your final location where you register the car. Don't know about any of the technical questions.

Kirby
http://greenhybrid.com/compare/mileage/car/1024.html