Hi Susan,I live in Yokohama and Yamate-cho is not so far from my place.
I checked the map ...and Bluff(Yamate) 179 is still there.
I'll call a realtor and ask if they know anything about the old families.
FYI
http://www.yyfj.net/index.htm
Although this site is in Japanese, you can see the pictures of that area today by pointing the cursor to the left columns that are showing the names of places.
I hope this will be a lead to your father's old friend!
Smile :) from Japan