I am looking for mint state Japanese AV Shu/ 2 Shu gold coins. Seems its easier to find FDC Roman Aurei then these John
If you had said silver Shu or Bu I could have helped with a dealer in Numismatic news. But even those were being offered as random types.
Crazily enough it can be easier to find mint wrapped and sealed packets of Koban than the smaller Shu or Bu - I recall some turned up in Japan and were auctioned. The Koban didn't circulate in commerce like the smaller denominations - they were more a store of value. Have you tried Clark Smith at Coinvault.com? He specialises in Japanese, Chinese etc.