Does anyone know what stone this is?
Kiita is yellowish, asagi is blue-gray, I can't read kanji, but usually Nakayama stones have different one. If they allow to test , do so and It might turn out a good stone.
here someone seems to have purchased similar stone
http://www.straightrazorplace.com/forums/hones/53548-new-hone-japan-pictures.html
may be they can tell you more