Great stuff Paul
I, too, lived in Japan for 18 months or so - split into two stints during the 70's and early 80's. I love the place. If I could go back to stay I would. I agree with Koputai - it's my favourite place in the world as well. I lived in Yokohama, near Yamate-Cho and just up the street from the famous Motomachi. From there we regularly took trips to Kamakura - my favourite place in Japan.
Another "fave" is Akihabara - the suburb of Tokyo (2 stations out) which is one giant suburb-wide electronics store. Fantastic!
Have a great stay - it'll get to you, too, when you have to leave.