Bizen Masamitsu was a pupil of Kanemitsu of Osafune village in Bizen province. His work follows that of Tomomitsu, Motomitsu, and Kanemitsu with gunome impressed on ko-notare hamon, although many of his swords are in suguha. His hamon are characteristically well defined and gentle, and the hada usually has somewhat cloudy and undefined utsuri like on this sword.
There are blades signed Masamitsu dated to the Enbun (1356-1361) and Meitoku (1390-1394) eras, and others, which are possibly by a second generation, in the Oei (1394-1428) era.
The curve of this naginata is elegant and reminiscent of that of the few surviving Kamakura-period pieces, although the blade is long and of the even breadth associated with both tachi and naginata of the Nanbokucho period.
The red-lacquer saya is from the Momoyama period and is a fine example of an elegant, yet unadorned mount that was intended for use.