Yes hiring a tour guide would make everything go 
perfect, and make the trip so much more 
enjoyable, this is the way to go, you should 
check with travel agencies, they can easily find 
a tour guide in Japan for you, it may be 
expensive but definitely worth it, if this is 
your first trip.

Also if your wife can read kanji, this will help 
out tremendously, at least you will have almost 
no problem getting around.

If you are eating out in a restaurant, you will 
need to have someone order for you, or 7-11 might 
be the only alternative, it is not easy but I 
think you will be ok.

Although Japanese are the nicest people in the 
world, and all so amazingly well mannered, but 
when it comes to dealing with foreigners, they 
may not be so nice at all, especially if you do 
not speak their language, some are still nice, 
but some are not, so be prepared, so there will 
be no surprise.

Hope you have a great trip