Longtime reader but first time poster here. I’ve learned a lot from other threads on this website, but recently hit a bit of a dead end in my own research. Any assistance translating the niji mei on this sword would be much appreciated. I've attached an image of the full blade alongside a yardstick marked with inches for scale, a closeup of the niji mei on the nakago, and a digitally edited version of the niji mei closeup showing just the characters in black on white for the sake of readability.
For my own part, I have searched the Nihonto Club database extensively but I haven’t found anything I recognized as a match for this signature. Two acquaintances of mine (one a native Japanese speaker and the other a specialist in researching antique Japanese ceramics) independently suggested that the signature might be “Kunisato”, but both of them also expressed that they were deeply uncertain about this interpretation. In my admittedly unexpert opinion the lower character looks more like 重 (“Shige”) than 里 (“Sato”), and the upper character has perplexed all three of us.
I’ve also been researching whether the nakago itself might offer some context clues as to the era this blade originates from in order to hopefully narrow the field of possible smiths. The side that the niji mei was chiseled into seems to confirm that this sword was purpose built as an uchigatana, rather than being a shortened tachi, and if I understod correctly, the short length of the nakago may indicate that it was originally intended to serve as a katate uchigatana, the single handed striking sword typical of the Sengoku period (though this example came to me in a two handed koshirae, presumably a later edition).
This sword is an heirloom that has been in my family for well over a hundred years, so I am interested in identifying the name of its maker to satisfy my own curiosity rather than for any commercial purpose.
Thanks!
Ty