Japan Travel 🇯🇵⛩️

I'm visiting Japan at the end of the month and we've found a few places that cater for gluten intolerance. My wife can't have gluten without getting ill and she's reading a lot of articles and blog posts that say it's basically impossible to survive in Japan on a gluten free diet. I've cooked plenty of Japanese dishes without gluten but I understand the soy sauce issue.

Does anyone have any tips for day to day gluten free living in Japan? Also any recommendations for places to eat in Tokyo, Hiroshima, Kyoto, Osaka and Hakone would be a bonus.

Thanks.