Thank you every body for your invaluable comments. Sorry the photos are not great.
Some history. I brought this some years ago because of the blade. all the blades I seen in bone were terrible just untampered metal.
The tsuka was glued to the tang of which I managed to gently to prise apart the seppa were made by myself from sheet brass.
As said the Yakiba is a Straight I can also see grain. it is very highly buffed to mirror finish.
For all the faults stated I seems to good for the bone fittings.
Thanks again for your help and knowledge.
David