trueing tool for KANNA?

[ROKUJURO]

I kindly ask for translation help for this tool I purchased in the hope it was a grinding stone:
 

but I have no idea what it is or how to use it.

Many thanks in advance!

[Shugyosha]

Hi Jean, it sounds about right:

 

鉋台 - Kanna dai - plane body

 

砥石の面直し器  - Toishi no tsuranoashi-ki - whetstone tool for surface flattening (sorry not the best translation but thereabouts).

[ROKUJURO]

Thank you John!

It is indeed TOISHI no TSURA NAOSHI-KI. It's a strange tool with a glass top and a fine soft surface underneath made of some foamy material - no whetstone in it, but it might be a stand to fix a fine sand-paper with water on the glass to level the bottom/sole of a KANNA.

Does that make sense to you? 
 

[Shugyosha]

Yes, it's similar to what I'd use in the west for truing up the sole of a plane. I don't know why it's described as a whetstone/ grindstone unless it's just the case that there's no word(s) more suitable in Japanese? Anyway, hopefully you'll receive what you think you've bought.