I took my own bottle of gluten free soy sauce everywhere I went - luckily nothing is weird in Japan. Most Japanese restaurants have a mini BBQ on your table and you cook the food. As long as we ordered without sauce this was great for me, expect the time we nearly set fire to the restaurant...

Of course it helped having two Japanese speakers with us to avoid those Lost in Translation moments, but with places like Coco Curry having an allergy menu, it's possible to visit Japan and eat out gluten free.
So although their return has scarpered my plans to return to Japan on the cheap, at least they're returning to Clapham where Hell Pizza deliver gluten free pizzas. So they'd better get used to much more frequent visits from me!