Nice stone. I have one that is nearly identical, though I lapped the kanji away since the chisel marks on the back were really deep. It is a very nice stone. I use it as a polisher before switching to my nakayama asagi.
I paid way less of course :D
IIRC I traded it for a box of Belgian chocolates.
Although I have to admit that it was a gamble, as neither I or the one sending it over had an idea of what I would actually get. So it was a bit of luck of the draw.