The generations of smiths named Nobukuni (信国) that followed the third generation are generally referred to as the Oei Nobukuni (応永信国)smiths. While there were several smiths of this name and most never reached the quality of the first three generations, there were two smiths among them that do stand out as far as superior workmanship is concerned. The first was Minamoto Saemon no Jo (or Genzaemon no Jo) Nobukuni (源左衛門尉信国) and the second was Minamoto Shikibu no Jo Nobukuni (源式部丞信国). While both of these smiths left wonderful blades, their skill never reached the zenith of that of the first two generations. Also since they made blades well into the Muromachi era, the overall shape and style of their blades make it possible to easily distinguish between them and the first two generations.
The first of these two smiths was also known as Genzaemon Nobukuni (源左衛門信国). This comes from the fact that he used the kanji character of “Minamoto” (源) in his signature and that kanji can also be read as “Gen”. It should also be noted that Genzaemon (源左衛門) incised the character “kuni” (国) in the manner of the so-called “hidari-ji” (reversed character). This is derived from the fact that the strokes in the box shape are executed in a reversed way that is opposite to the way it is written in the other Nobukuni (信国) smiths’ works. For more information about this and the other Nobukuni smith, please visit the following article, Nobukuni.
This sword is an ubu (unshortened) tachi attributed by the NBTHK to one of the Oei period Nobukuni smiths. The sayagaki by Tanobe Sensei, formerly a director of the NBTHK, goes even further and states in the sayagaki that this is the work of one of the two most famous Nobukuni smiths of that period, Saemon no Jô Nobukuni. The sayagaki is translated as follows:
The blade has an ubu-nakago and is mumei. It is a masterwork that shows very well the characteristic hardening in gunome-midare of the Ōei-Nobukuni group. The masters Genzaemon and Shikibu no Jō Nobukuni were active at that time and this blade is a work of the former.
Blade length ~ 68.8 cm
Written by Tanzan Hendō [Tanobe Michihiro] in the tenth month of the year of sheep of this era (2015) + kaō
It is a very beautiful and strong sword with a cutting edge as mentioned above, i.e. 27.125 inches or 68 cm. It has a moto-haba of 1.24 inches or 3.1 cm and a saki-haba of 0.8 inches or 1.9 cm. It has a graceful torii sori measuring 0.93 inches or 2.4 cm.
The jigane is typical of the Nobukuni group being a itame that is hadatachi. The hamon is nie based and is gunome-midare with a bright nie-guchi. There are profuse clouds of nie on and above the habuchi and there is sungashi and kinsuji within the hamon. The bôshi is somewhat pointed on one side and mildly hakkikake on the other. There is a very short kaeri on both sides. There are bo-hi on both sides that extend down into the nakago. The nakago is ubu and the blade is unsigned. There is a gold-wash tachi habaki.
This blade comes with NBTHK Tokubetsu Hozon papers attributing it to the Oei Nobukuni group who worked in the late 1300’s to early 1400’s. Also, as has been noted, the sayagaki by Michihiro Tanobe Sensei further attributes this blade to Genzaemon no Jô Nobukuni.
This blade is accompanied by a set of 20th century Itomaki no Tachi Koshirae that was ordered by its last owner. While the quality of this koshirae does not compare to the older Edo period, it is very pleasing to the eye and will make a lovely display to go with the wonderful 600 year old blade.