Have they got invoices backing up the stamps in the book? Admittedly this may not help much though as it'll be in Japanese.
Due to the strict MOT rules in Japan, I will suspect it's had everything done. As I believe everything has to work on a car in Japan for it to pass an mot.
Make sure the seller is changing the language to English on all car systems. As this can be an issue otherwise.
I see your in Ely, if that's London I'd highly recommend you get the supplying dealer get you a certificate of conformity from VAG as this will help prove the cars emissions regarding ULEZ.