Mine was bought new, not by me, from the Channel Islands in 1996 (I have the first tax disc from May 1996 issued in Guernsey in its history) and then 'imported' into the UK mainland two years later. My V5 says, in Section 3, 'Special Notes (these notes cannot be removed)', on the first page:
1. Was Registered Overseas Declared Manufactured 1996
and then on page 2:
4B Date of first registration 11.03.1998
4B.1 Date of first registration in the UK 11.03.1998
I guess similar wording would apply to any import including Japan, unless anyone knows differently.