Tokuzenin Sadamune (Unsigned Sadamune)

Sadamune (active early 14th century) worked in Sagami Province (modern Kanagawa) and is traditionally ranked as the foremost of the "Masamune jittetsu" (ten great disciples of Masamune). He inherited the deep, tempestuous nie of his master Masamune but refined it into a more composed, aristocratic style. His tanto in particular are renowned for hamon closely resembling Masamune's work, graceful looping boshi, and superb steel quality.

This unsigned (mumei) tanto takes its name from Maeda Gen'i (1539–1602), one of the "Five Commissioners" (Go-bugyo) of the Toyotomi administration, who held the Buddhist title "Tokuzenin." A senior retainer to both Oda Nobunaga and Toyotomi Hideyoshi, Maeda Gen'i is said to have owned this blade, which subsequently passed to Hideyoshi himself, then through the Tokugawa shogunal house, the Kishu Tokugawa branch, and the Saijo Matsudaira clan.

The blade carries relief carvings of sankosho (vajra-hilted sword), incense burners, and Sanskrit characters on both faces. The steel is a tightly packed ko-itame with rich nie, and the hamon with its elegant boshi (tip temper line) reflects the refinement Sadamune developed from Masamune's model. Though unsigned, the blade has been authenticated by the Honami family as a masterwork of Sadamune.

Designated a National Treasure on November 22, 1952, the sword is now held at the Mitsui Memorial Museum in Chuo Ward, Tokyo, where it is exhibited at special exhibitions. It stands as an essential reference piece for understanding the Soshu tradition and Sadamune's place in Japanese sword history.