Hey Bratch, my wife is Japanese too and as you know the CW in Japan is very much rice, rice, rice. I too had a hard time explaining way I wanted to go primal and although I've only recently got properly serious the results so far (especially on mood and blood sugar) have my wife convinced. She is now nearly as primal as me and life is good.
I did a search for the appropriate Japanese phrases although pasting them here might result in the Japanese text going strange. The best things to search for on the internet for Japanese viewers are:
1. tei inshurin daietto (low insulin diet)
2. genshi jin daietto (palaeolithic diet)
3. pareo daietto (paleo diet)
Sadly, there isn't too much information out there in Japanese. The way I explained to my wife is that simple carbs cause your blood sugar to rise and then crash. I asked her to try it for a week and she was totally convinced. If you live in Japan the most difficult thing is finding the ingredients but modern day foraging is part of the fun.
This is the only Japanese book I found (search for the ISBN on Japanese Amazon (co.jp).
ISBN-10: 4106005131 (Genshi jin kenko gaku)
Good luck! JpGrok