The artist Masamune was a master swordsmith of Sagami (present-day Kanagawa Prefecture) in the late Kamakura period (1185-1333). Having adopted the lifestyle of a monk but not having taken orders, he went by the title "lay priest" (J. nyûdô) and was known as "Lay Priest Gorô." His work includes both wide and narrow swords. This narrow katana blade is a beautiful piece, recalling tachi swords of the Kamakura period, which were an older type of curved sword worn with the blade down. With its richly varied metal finish (J. jigane) and tempering pattern (J. hamon), the work stands out even among Masamune's masterpieces.
Hon'ami Kôtoku, a sword connoisseur of the late Momoyama (1573-1615) and early Edo (1615-1868) periods, authenticated this sword as Masamune's work. In 1609 (Keichô 14), when the sword was sharpened and polished by Umetada Jusai, Hon'ami gave it a gold inlay inscription reading, "Owned by Jô, Lord of Izumi, shaped by Masamune; [signed] Hon'a." This "Jô, Lord of Izumi" was Jô Masamochi, a vassal of the warlord Takeda Shingen (1521-1573), who served the shogun Tokugawa Ieyasu (1542-1616) following the destruction of the Takeda clan. The sword later became the possession of the Tsugaru family of the Hirosaki Domain.