I am going to Tokyo, Japan next week. If you want, I can give you tips and maybe contact information of people in Japan for you to get in contact with?
I did not have much luck in finding other deaf people, but I think I have found guide who is an interpreter working on developing skills.
I am going to write blog about my trip when I get back.
But of course I won't know for sure until I get there.
When I get back, I can try and see if I find this thread again and hopefully post in it with information that you were seeking.
But for now, my biggest advice is to start planning NOW. Don't be like me waiting until merely few months beforehand especially with foreign countries. You want to be able to find good seat in airplane, contact hotel to see if they have room, and to see if they do speak English. That was one of those thing I looked when I searched for hotel, to see if people there can speak some English.