Hi,
Have you tried using the Google Translate app in camera mode?
You can get some quite amusing translations but it will eventually show something sensible.

I used VJMC's dating service to get my bike dated for registration, its worth the subscription fee to join as well. The DVLC always knock the reg plate back a year though because its always dated from the beginning of the year not March of that year, but if that is a Japanese equivalent of our V5 then you will have evidence of a month which it was registered, so an R reg won't become a P...