Yamatorige (山鳥毛, "feather of a copper pheasant"), equally known as Sanchōmō by its Sino-Japanese reading, is a tachi (Japanese greatsword) forged during the middle Kamakura period (13th century). The set of the blade and its koshirae (mountings) is a National Treasure of Japan. It was wielded by Uesugi Kagekatsu (1556–1623), a powerful warlord in the Sengoku period, and had been inherited by his clan.[1]