The Museum of Japanese Sword Fittings, ed., Kaikan san-shunen kinen tokubetsu ten, meimon kinko Goto-ke no ishizue (Exhibition commemorating the third anniversary of the museum's opening, important works from famous metalworkers of the Goto family), exh. cat. (Tokyo: Museum of Japanese Sword Fittings, 1997), no. 25, p. 18.
_______, Tokubetsu ten, koto meisaku ten, tosogu meihin ten (Special exhibition of masterpieces of early swords and sword fittings), exh. cat. (Tokyo: Museum of Japanese Sword Fittings, 1999), no. 7, p. 7.
_______, Tokubetsu ten, Kamakura jidai no meito ten (Special exhibition of masterpieces of swords from the Kamakura period), exh. cat. (Tokyo: Museum of Japanese Sword Fittings, 2001), no. 9, p. 14.
This tanto was awarded the rank of "Yushu Bunkazai" (Excellent Cultural Property) by the Museum of Japanese Sword Fittings in 2001.
The tang of this dagger bears a vermillion lacquer attribution by Hon'ami Choshiki to the late Kamakura-period master Masamune of Soshu, the greatest of all Japanese swordsmiths. Masamune's work is technically unsurpassed, with a deliberately contrived beauty arising from an intimate mix of hard and soft steels. The technology must have owed much to the cross-fertilization of ideas among smiths from all over Japan who went to Soshu to supply the demand for swords there during the Kamakura period. Old documents tell of Masamune being the son of Yukimitsu, and that he had ten pupils, among whom the greatest was his son, Sadamune. But it is not wholly clear what the relation between the early Soshu smiths was. It is likely that Masamune was taught by Shintogo Kunimitsu, together with Shintogo Kunihiro, Yukimitsu, and Norishige, and that the generation traditionally known as "Masamune's pupils" studied under this group. The work of Yukimitsu, Masamune, and Sadamune in particular can be very close, and old attributions of unsigned pieces to these three smiths in particular have always been accepted out of respect for tradition.
The unmistakable and distinct early Soshu-school characteristics of this tanto can be compared with other well-documented and famous blades. It is, for example, close in dimensions, overall shape, and hamon, to the Tokubetsu juyo tanto illustrated as no. 63 in Koto shinto meihinshu (Collection of early and later masterpiece swords) (NBTHK 1976), which bears a vermilion lacquer attribution to Yukimitsu by Hon'ami Mitsutada. The blade is also very close in dimensions and hamon to both the National Treasure known as "Terazawa Sadamune," and to the important "Taikoji Sadamune." The suken horimono (Buddhist sword) in the bohi on the omote of the Taikoji Sadamune is particularly comparable in style and position to that of the Choshiki Masamune, although the latter is rather worn. The Choshiki Masamune tanto has a degree of machiokuri, and if this is considered when comparing the two blades the similarity becomes more apparent, even to the positioning of the two lower (and older) mekugi-ana.
The inscription on the shirasaya may be translated as:
The grandmother of the Arita [family] was a daughter of the Takamuro family who served Lord Ota of Kazusa Province [present-day Chiba Prefecture] for generations. Their ancestor was Saegusa Kageyuzaemon. Saegusa was from Koshu Province [present-day Yamanashi Prefecture] and was a follower of Lord Kizan. Takeda. This sword was given to him by Lord Takeda for his military excellence. Later, when the aforesaid daughter of Takamuro married into the Arita family she brought this sword with her, and the Arita made it a family treasure. This history is written in spring of the second year of the Meiji period , when the sword was polished.
Although Hon'ami Choshiki does not have a reputation for diligence in his attributions, this fine blade is of the period and in the Soshu style of Masamune and his immediate successors.