Katana signed by Yasutsuga with cutting test, NBTHK Hozon certificate - Kanbun-Enpo era (1661–1680 -

JAPAN - Kanbun-Enpo era (1661–1680), marking the beginning of the Edo period.
Samurai katana.
FUSHI and KASHIRA made from a single piece of finely chiseled copper, patinated and gilded, decorated with red-crowned cranes (prestigious animals whose hunting was once the exclusive privilege of the Tokugawa shogunate).
Wooden TSUKA covered with stingray skin and blue silk cord.
MENUKI made of chiseled copper, patinated and gilded, decorated with chrysanthemum flowers (a symbol of autumn and longevity) and vine leaves (karakusa, also a symbol of longevity).
Maru-gata TSUBA made of wrought iron, openwork, and inlaid with gold, decorated with pine needles (a symbol of unity and harmony).
SAYA made of brown lacquered wood, kurigata featuring the pine thorn motif, with a silver kojiri.
Simple copper HABAKI.
Straight blade, regular hamon—straight and well-defined; the tang has three holes and bears several inscriptions;

The signature of the third-generation Edo Yasutsugu.
The Tokugawa clan’s mon, a privilege granted by the shogunate in recognition of a high-ranking swordsmith.
A “Saidan-mei” inscription indicating a cutting test performed by Yamano Kanjuro (active c. 1661–1673).

Sold with its stand, silk carrying case, and NBTHK Hozon certificate. NBTHK, also known as Nihon Bijutsu Touken Hozon Kyokai (the Society for the Preservation of Japanese Art Swords), is one of the oldest organizations for the appraisal of Japanese swords in modern Japan.
Dimensions: 97 x 9 x 9 cm.
Blade length: 69.3 cm.
Curvature: 0.75 cm.

Notes: The founder of the lineage, the first-generation Yasutsugu, is believed to have been born in the town of Shimosaka, in what is now Shiga Prefecture, during the late Muromachi period (late 15th century). He established his career there until the beginning of the Keichō era (1596). Due to the relocation of the lord he served, he later settled in Echizen Province, where his talent caught the attention of Matsudaira Hideyasu, the third son of Tokugawa Ieyasu and feudal lord of Echizen at the beginning of the Edo period.
Under Hideyasu’s patronage, the first-generation Yasutsugu founded the Echizen Shimosaka school, whose reputation quickly spread nationwide. On Hideyasu’s recommendation, Yasutsugu was appointed Okakae-kaji, the official blacksmith responsible exclusively for forging blades for the Tokugawa shogunal family. His work was highly esteemed by both the first and second Tokugawa shoguns, Tokugawa Ieyasu and Tokugawa Hidetada.
In recognition of his exceptional skill and reliability, the first-generation Yasutsugu received the character “Yasu” directly from Tokugawa Ieyasu—an extraordinary honor that led him to adopt it as an integral part of his smith’s name. Furthermore, he was granted permission to inscribe the Tokugawa family crest on the hamon of his blades. At the time, the Aoi-mon was a powerful symbol of shogunal authority, and only a very small number of swordsmiths were permitted to use it. This privilege clearly demonstrates that Yasutsugu was regarded not only as a skilled craftsman but also as a swordsmith of the highest rank, entrusted with embodying the authority and dignity of the Tokugawa regime.
Furthermore, this sword bears a Saidan-mei inscription, or cutting test inscription. A Saidan-mei is an inscription engraved on a blade to record the result of an official cutting test conducted during the Edo period. These tests were performed to evaluate the sword’s cutting performance and were an important factor in determining the blade’s reputation and value.
During the Edo period, cutting tests were performed on approved materials, which could include bundled materials or, in some cases, the bodies of executed criminals. These tests were conducted by officially appointed specialists, and when a blade demonstrated exceptional cutting ability, the tester’s name was sometimes engraved on the tang or the blade itself.
The name of the cutting tester engraved on this sword is Yamano Kanjüro, who was active around the Kanbun era (circa 1661–1673). He was tasked with conducting cutting tests by official order on swords carried by the Tokugawa shogunate, including those worn by the shogun, given as gifts, or officially presented. This role was known as “O-tameshi goyo,” meaning an officially sanctioned mission for cutting tests.
Later, this role was taken over by the Yamada Asaemon family, who became one of the most famous sword testers and executioners in Edo-period Japan. Yamano Kanjürõ is considered one of the first figures to hold this position of authority.

Ref: 7BEKM7I9IZ