Hi,
I've this wakizashi, which is an American loot during WWII, ō-suriage with kaō in black urushi and other remains. But first of all it's a sword with a very interesting hamon and hataraki.
Given your experience have you ever seen attributions in black lacquer? Given the wear, however, it may have lost a superficial part (maybe red/gold..?!), it is difficult to say. Furthermore, by hypothesis, it seems to me difficult that the ancient red lacquer due to sun exposure and aging, can be darkened so much and homogeneously on both sides of the nakago.
The kaō looks similar to that of Hon’ami Tadamasa, but even if some strokes are missing, and I don't think they disappeared due to wear. Maybe in his career he may have made changes to the kaō, but unfortunately I find only this image:
And on the opposite side 1 kanji stands out relatively well, there are small remains of at least one other kanji. --> "津" from Shizu "志津".
The old sayagaki can come in handy, in fact the attribution to Naoe Shizu is reported.
The sayagaki I think is honest. Furthermore, as you can see from the photos, it doesn't any kaō on the sayagaki, only the attribution and size of the nagasa.
Can anyone help me identify the kaō?
Thank you,
Francesco