A Daimyo owned Kotetsu, registered in Showa 26 (1951).
A daimyo blade is indicated by looking at the Japanese sword license, the torokusho.
This has the date the blade got licensed and many top blades from Daimyo Collections were licensed in Showa 26 (1951). Daimyos were the feudal lords of old Japan.
In that year, the Japanese government implemented a law requiring all swords to be registered and licensing begins on a small scale and daimyos were asked to register their collection of swords and set a precedent. Swords in a Daimyo collection are of superior quality and much sought after by collectors.
It is the opinion of many and recently a very prominent sword dealer that the quality of this sword is of top quality and the signature though looking good, would still better be verified by the experts at NBTHK.
This is a top quality sword registered in Showa 26 (( so called Daimyo registration year). The the jigane on this blade looks like velvet.
There is a similar Kotetsu sword in a Japanese sword magazine as depicted in photo 2.
The koshirae itself is a beautiful piece of art with rare big same with dragon matching set Kozuka-kogai, Fuchi-Kashira and a big signed iron Choshu tsuba.
The Daimyo registration licence is a provenance of its importance and a further comfort that some sword experts who have examine it agreed that it is a very high quality sword. However, with all big name swords, it would be good to be authenticated by the experts at NBTHK.