Since the site is pretty inscrutable, I figured I'd start a reference thread with links to sellers that carry interesting stuff - saves us all some time.
Do add stores you've found too!
Lists of brands the stores carry are not exhaustive, they're just what I managed to ascertain.
Carries Masamoto, Sakai Takayuki (including crazy stuff like a 300mm honyaki deba!)
Carries Suisin Inox Honyaki, other unidentified Sakai makers
Carries Yoshikane, Tojiro, Sugimoto
Carries Shigefusa, Tsukiji Masamoto
Carries Misono, Hiromoto AS, Masahiro, Masamoto
Carries Masamoto, Misono, Aritsugu, natural stones
No knives, but really fancy tableware
Let me know what you find!