As Shell 156 said you need to learn some of the words. Ko mugi ko is wheat flour where as ko mugi is wheat. Another way to say no wheat or flour is meriken ko or american powder. Takashi Imai <email@example.com> is my old friend there in Yokohama who is a doctor and understnads celiac. Ive had a place in Japan for more than 30 years and commute between there and hawaii.
Bring your own soy sauce -- soy sauce in Japan is wheat and many chefs dont understand that ..
JU wari soba is 100% buckwheat but regular soba is not . what hotel are you at.
www.musmus.jp is mostly veggie place i was at in nov. and good and all you do is tell them komugi allergy -- allergy is-- al ru gi
You can ask the hotel to help you say it correctly.
shoyu ( soy sauce) dame (daa May) means you cant have soy souce
download the free travel cards in japanese too.
have to run now but will try to add more in the next few days..