I don't know anything about buying in Tokyo but I purchased an M5 from Sherry two years ago and it has become my favorite film camera. I have been owning and using Leica's since 1974 and had always wanted an M5 since it was THE Leica to own while I was shooting Nikons in college. Well, I have owned all the other film M's except the most recent M7, MP and MA.
Talking to Sherry is always a hoot and when I found out she had a recently serviced M5 for sale, I had her stick a third lug on it and recover it. Then I had her send it. It is presently my only film Leica as I just sold a nice M2 I had purchased from her about the same time. If she has serviced it, it will last another 50 years. And just for information, I sold the M2 to a gentleman in Sydney and shipping and tracking from the US was $80 via USPS but delivered in five days from here in Texas with tracking info enroute.
As I explained over on LUF, the M5 just works for me being the last Leica M made to classic standard before the M4-2, having a TTL light meter like I was similar with back in the 1970's, modern film loading and a viewfinder whose clutter is more then the M2 but less then anything since the M4-P. As the head bartender says on his site, Leica spent years designing the M5 to correct shortcomings in the M2-M4 but they misjudged the market. And I recently acquired an MP240 and the M5 is not any larger. And with the 50f1.1 or 35f1.2 Nokton on the front, it is a formidable outfit both in weight and capabilities.
So, if you want an M5 I say go for it. If you don't need to purchase in Tokyo, I strongly recommended Sherry Krauter at Golden Touch Leica! Or have fun on your hunt for an M5 in Tokyo.