What is this Japanese tool?

[Edwin Santos]

Hi,
This is like a Japanese tool version of "What is It" on Ask This Old House.

I recently visited a shop in Tokyo called Hamono Inoue, which I'm told is one of the few if not the last of the shops in the city that deal in high quality woodworking tools.
While there I picked up a few very nice dovetail chisels and this exotic looking tool. The owner speaks a little English but not enough to be able to tell me much about it in any great detail.
I speculated that it might be used for cleaning out a mortise like a very narrow, sharp, bent neck scraper, so I bought it on this hunch. But perhaps that's not the intended function or there is simply more to this tool than I presently know.
So if anyone here can tell me more about it, I'd appreciate it. It's about 6mm wide. Thanks
Edwin

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[Vincent Tai]

Sokozarai Nomi.

A quote from a post by Stan Covington in a thread on this forum: 2. The Joinery Mortise. Used for more delicate members, and where precision is more important than speed. This mortice is layed out with a steel square, marking gages, and a marking knife. A V is cut almost to the bottom. The sides are not worked unless the fibers are intertwined, and the chips don't come free. The ends are left a few thousandths fat, and the chisel (often a sukinomi) is used to pare to this line. In some cases, and in softer woods, the ends are not pared square with the surface, but slope to the centre so the end of the tenon is compressed when driven home. A sokozarai nomi ("bottom scraper chisel") is used to clean out waste, tidy up the corners, and shave the bottom to the proper depth. In the case of shoji, the thickness of the wood remaining at the bottom of the mortise may be only 0.05 millimetre (light will shine through), so precision and this specialised chisel are indispensible.

https://sawmillcreek.org/showthread.php?239497-The-Japanese-way/page2&styleid=4

I remember theres a thread that goes a touch deeper but its impossible to find half the things on this forum even with google. Brian can fill in any missing detail though as he actually owns and uses these.

Vincent

[Edwin Santos]

Vincent,
Thank you for the excellent information. Now that you have educated me on the name of the tool, I have found more information about it online. I'm glad I took a chance and bought it.
Edwin