It certainly feels like a Nakayama, and that would be my guess, but I'm not a guru like you guys.Yes, but there's no way to prove it, not enough 'skin' on it. The karasu pattern is sharp edged and high contrast, and the stone is hard, so that proably puts it at least in the mines in the close vicinity of Nakayama. But it just does something nice to an edge that seems to belong to Nakayamas more often than other stones.
Cheers, Steve