Where to Look in Tokyo to Find Old Kamisori Straights?

I’m going to be traveling for the first time to Tokyo. Can anyone tell me where I might go to find old kamisori razors? If someone were to ask me that question when traveling to the US — where to go to find old razors — I’d suggest antique shops or estate sales. I don’t know about such practices in Japan. I’d be over the moon to stumble upon a pre-WWII blade in good shape when I’m there. Does anybody here know where to go? Thanks for any suggestions.

edit:
Also, can people suggest any marks/imprints/tells to look out for, both positive or negative?

I’m going next month too. I am curious for any shops that sell straights, kamisori or regular.

There are a lot of flea markets in Tokyo, but they are open highly irregularly (like every third Sunday of the month etc.)
I found some kamisoris in the market at Hanazono Shrine in Shinjuku, which is open every Sunday.

Yep, the flea markets are the best places to find razors and hones. Almost no one in Japan shaves with straights.

You can check out some of the larger hardware stores. Some sell Kamisori more as curiosity items.