David Weaver
This is an older early japanese attempt at a strong cutting white alundum sharpening stone. I can't tell if it's resin or vitrified, I would imagine it's a resinous stone, but a little porous. It needs water and a slurry or it loads quickly.

If one finds a group of sharpening stones in japan, you come across early fine synthetic stones. Lots of them. The idea that kings were something new is sort of weird, especially given synthetic alumina razor stones with binder have been around since at least the early 1900s.

This stone would've probably been described as JIS old standard of 5000 or 6000. It would work better if it was wet all the time.

The cost as part of a group was probably less than $10.