Naginata Signed Bizen-no-kuni Osafune-jūnin Nagamitsu Zō

The Naginata Signed Bizen-no-kuni Osafune-jūnin Nagamitsu Zō is a National Treasure forged by Nagamitsu, the founding master of the Bizen Osafune school. It measures 43.3 cm in blade length with a curvature of 1.8 cm, a motohaba of 3.2 cm, and a tang (nakago) of 63.6 cm, and it retains its original, unaltered tang bearing the smith's signature — a major point of its value. Naginata were frequently worn down through hard battlefield use from the Kamakura through Muromachi periods, making it extremely rare for an example from this era to survive intact with an unaltered, signed tang. This blade is also noted for the excellence of its steel and temper, and it is highly regarded as a benchmark work conveying Nagamitsu's skill as the leading master of the Bizen Osafune school. It was transmitted through generations of the Matsudaira lords of Tsuyama domain in Mimasaka Province before entering the collection of the Sano Museum of Art in Mishima, Shizuoka Prefecture. It received Important Cultural Property designation on May 25, 1937, and was elevated to National Treasure status on February 19, 1957. As a museum holding, it remains a precious surviving example of a Kamakura-era battlefield naginata.