Attached is a scan of Isezaki-cho (from a postcard that I found in Castro Street, Mountain View, Calif.).
Check out the Gi's hanging out in the lower right & the auto's. I would say it is in the late 40"s for sure. [Confirmed - and yes that is the PX as you mention later on - Jim Hyatt]
Some interesting facts about Isezaki-cho. You would get there by trekking from Negishi through Dirty Village (Yama-mate-cho) to the street car station (end of the line) - take the streetcar down the hill - get off near the cinema Toho Megaza (still there in original condition) on the corner of Isezaki-cho. Then walk down Isezaki-cho until you hit Kannai - where this photo is taken.
On the left side APPROX. 25 METERS into Isezaki-cho is the famous bookstore Yurindo (started my stamp collection there) & on the right approx. same distance is the Nozowaya department store (original PX according to the older folks). I believe in 1971 or so, the 1st McDonalds in Yokohama was on the ground floor of Nozowaya (or next to it). I worked (with a few friends) during the summer of '70 or so for Nozowaya, hand wrapping O-chu-gen gifts.
FYI - I graduated Yo-Hi in '74 but lived in Negishi since 1st grade going to St. Joe then moving to Byrd in 3rd grade.