I've investigated this process for Japan albeit a few years ago, as we have a house there (my wife is Japanese).
The cost for a classic Honda was then around £1,600 for registration, compulsory insurance for road use and the "Shaken" inspection. Shipping is not included in this cost. The costs for a particular machine can be established by the shipping agent submitting the VIN and other details to their import facility in Japan. They can then determine eligibility and charges.
I do remember at the time that there was a clear cut - off point for manufacture (2004 I believe) after which the process became MUCH more expensive (around £6,000 for a typical motorcycle) due to the need to comply with more legislative requirements.
Do remember that if the bike is over 400cc then a special (and difficult to obtain) licence is needed to ride it (I think that the test failure rate is over 80% at first attempt, and very few establishments can offer the necessary training) and that spare parts for the larger capacity machines will probably need to come from outside of Japan, even if the machine was originally made there, as it probably was not offered to the domestic market.
From memory, it was also a requirement that the importer was entitled to residency in Japan.
In short, unless there are very strong reasons for taking a particular bike or car over, it's probably not worth it for your own use.
Of course, if you are selling the bike to a Japanese citizen, it might change everything!
