I went to a travel expo on Saturday and thought of you both. I found some Japan specialists and wonder if you've looked on the web at
www.jalpak.com which is the US section of the company. I phoned the people at our local office (very Japanese who said I talked too fast) but they thought that as long as Marty wasn't completely disabled, a normal escorted tour might be OK. On most of their tours, you have to look after yourself. Perhaps you could phone your local office and hopefully they may have some suggestions. A lot of the optional tours include walking plus stairs (I can vouch for both). Would Marty consider a wheelchair?
I do know that unfortunatley Japan is not a destination for the disabled but if it's something he really wants to do, would you consider flying into Tokyo, Kyoto, Hiroshema and taking day trips plus a taxi or two? The bullet train is ideal (very expensive) and I know we encountered stairs when we went on it but maybe they have a lift.
Do you have a Japanese tourist agency over there who could help?
Hope you can work something out.