Had a root canal treatment earlier today so I will be brief as I don´t want my painkillers to gain the upper hand over my writing. In my article on the Musashi-Masamune I presented four different oshigata to the very same blade. As I had to look for something in older Token Bijutsu magazines, I found another oshigata to a blade of Kotetsu I introduced in my recent publication Shinto & Shinshintô-kantei (number 236.665). I was surprised how different the reproduction of the monouchi section is. Well, we can agree that the bôshi and the connected gunome-protrusion right before the yokote match but then it seems that the hamon take way a different course. It seems at a glance that the hamon on the upper oshigata is slightly compressed but after a closer look we learn that also the course after the second connected gunome-protrusion differs. At the upper oshigata, four bumps follow after the protrusion before the hamon lowers a little. At the lower oshigata, there is one large bump and two smaller before the lower section starts. Just on the basis of these oshigata alone I would say we are facing two different blades but I double-checked the descriptions. Both blades have exactly the same measurements and exactly the same tameshi-mei. Please not that at the lowermost oshigata of the tang, the maker saw a kind of yakikomi at the habaki area whereas the hamon continues as suguha and even goes down on the upper oshigata. For your information, the oshigata I used in my Shintô & Shinshintô-kantei was published in issue 665 (June 2012) of the Token Bijutsu. The other one is from issue 581 (June 2005). So I guess the differences can´t be explained by a new polish.
Picture 1: Comparison of two Kotetsu-oshigata. The uppermost monouchi-oshigata belongs to the lowermost nakago-oshigata.
The top character on this Kotetsu oshigata looks similar to the ‘last name’ character on a possible Hizen Yoshinobu. Could this one be possibly a dimei of Yoshinobu of the Tadayoshi School and Kotetsu? …as this additional ‘masa’-like’ arc makes the blade look like a gimei Yoshinaga …as the ‘naga’ looks more like the one used in Kotetsu’s ‘Nagato’. It’s interesting to see. Yamashiro+Umetada+Tadayoshi School = drama.
Karl, I guess with ‘Nagato’ you mean ‘Nagasone’? Kotetsu had no link to any Yamashiro, Umetada, or Tadayoshi school smith as he was based in Edo and active significantly later, i.e. around Kanbun (1661-1673). Apart from that, to execute/write the bottom part of the character for ‘Naga’ in a somewhat roundish manner was very common. Please browse through the 20 or so pages of the following link: