This is a wonderful katana made by the Kishu Ishidô smith, Yasuhiro. The full signature reads Bitchu no Kami Tachibana Yasuhiro (備中守橘康廣). There is also a kiku (chrysanthemum) crest on the ura (backside) of the tang. The first generation Yasuhiro, who made this katana, was the second son of Tosa Shokan Tameyasu and the brother of Omi no Kami Tameyasu. Yasuhiro was very good at making swords in the Sôshû style. He was also very good at making Bizen style swords with chôji midare hamon. He worked around the Kanbun era or 1661.
This katana is a masterpiece showcasing his skill in the Sôshû style. It has a deep nie-guchi gunome midare style of temper with many activities such as kinsuji, sunagashi, and it even has midare utsuri. If you want to really get an idea of what kinsuji is supposed to look like, this is the sword for you.
The sword has a cutting edge of about 24 inches which equates to two shaku or the minimum for a katana. The jigane (grain of the blade) is ko-itame hada with ji-nie and thin lines of chikei. The hamon is nie-deki (Sôshû style) with a gunome-midare covered in nie and lots of kinsuji and sunagashi as has been mentioned. The width at the hamachi is 2.95 cm or1.16 inches. The width at the kissaki is 2.23 cm or 0.87 inches. The kasane (thickness) is 0.63 cm or 0.24 inches. For further information about this smith and this school, please refer to the following page of this website, Yasuhiro.
This sword comes with an outstanding set of koshirae with all of the metal fittings done by the Soten School. The tsuba is signed from the Soten School. It is made of iron with deeply carved images of Samurai in battle. They are decorated with gold, silver, and copper. The fuchi and kashira are also signed Soten School pieces and the carving is even more refined and beautiful than that of the tsuba. The menuki are of shakudo with the same motif of Samurai. All in all this is a very impressive and beautiful set of mountings that are in excellent condition and of top quality.
This sword comes in a shirasaya with a tsunagi (wooden sword) in the koshirae so that it may be displayed separately. The blade has NBTHK Tokubetsu Hozon papers attesting to its quality and condition.