Many thanks George, very helpful. Will look-out for Sato Shigenori.
On the subject of Shibata Ka, there is of course Darcy's excellent link
and I seem to recall Ted Tenold praising Ka somewhere on the Forum too.
Interesting example of Shibata ka's work visible here:
Shibata Ka is also twice mentioned in the book 'The New Generation of Japanese Swordsmiths ', first on page 219 in relation to excellent jigane mistakable for koto work, (The same passage quoted on Darcy's page I think). And then in the section interviewing the celebrated sword dealer Shibata Mitsuo, where Mitsuo mentions problems with Ka's swords having flaws and an exhibition being cancelled circa 1932 (unsure of page number off-hand).
Could these problems have been related to experiments with forging, leading to flaws that may have been acceptable in Koto pieces, but which were unacceptable in newly made swords (?)
One further thought related to Shibata Ka, is the 'Ka' (果) character related to 'apple'? If so that could be an interesting connection with the apple growing culture of the Tohoku region. Beyond that, it is interesting to consider the relationship between tool-making and sword smithing. For a contemporary view on tool making tending-towards-sword-smithing, see:
http://www.tokyoartbeat.com/tablog/entr ... zosho.html
Apologies to readers for the incorrect splling to the title of this thread. I was tired from too much internet-based hypothesizing and a lack of decent reference material. More investment in lit urgently needed on my part.