so, I have a friend going to Yokohama in April and...

[someonenameddavid]

I wondered if there was a good camera store that might have a decent Nicca, Leotax or whatever Leica screw mount that wouldnt cost a bajillion Yen

 

[Yokosuka Mike]

"Camera Ohnuki" near Hinodecho train station is a good placed for your friend to look.

https://www.camera-ohnuki.com/netshop/

All the best,
Mike