[schroth-sensei]

Welcome to tabifolk!
First, if you need some tips on the flight itself, check out this article: Tips on Traveling to Japan with a Hearing Impairment
You probably know this already, but Japanese Sign Language (JSL) is different than American Sign Language (ASL), so you can’t count on ASL for communication. Good news is that there are free translation apps available that you can type your message through, so it’s recommended you rent a smartphone or sim card if you have an unlocked phone. More information in the Internet Access when Visiting Japan section of Accessible Japan. Apps I recommend:

• Text Translator app to/from Japanese, Google has a free app and it is very useful in many situations (many of the train attendants have them too and will occasionally use them if they can’t get what they are saying across). The translation isn’t perfect, but if you keep sentences short and to the point then it should translate well enough. As for explaining situations like food allergies (or disabilities), I would instead recommend using Accessible Japan’s Essential Japanese Phrase section to construct and print a physical copy of your concerns in both English and Japanese, leaving little room for error.
• Another useful app for non-Japanese speakers is a Text Translator from Image app, Google again has it, you will quickly find that shopping for food at a supermarket is much easier when you can read labels. With it you can use your camera to translate in real time, then you won’t mistake a bottle of vinegar for a bottle of cooking oil, or which box with a cow on it is cheese or butter. I was glad to have this for those reasons and more.
• Maps, standard on phones. This is very useful for figuring out train fare, finding restaurants, and helpful in pointing out where you want to go to a train attendant.

I hope that helps, but if you have any other questions please feel free to ask and we’ll try to get you an answer.
-Justin