The sword is designated as a Juyo Token [An Important Sword] by the Nihon Bijutsu Token Hozon Kyokai [Society for the Preservation of the Japanese Art Sword].
It is recorded in ancient documents that Bizen Saburo Kunimune was the third son of Kunizane, son of Naomune of Bizen Province, hence the name Saburo [third boy] Kunimune.Another theory is that he was the son of Ichimonji Yukikuni.He was summoned to Kamakura by the Kamakura governor Hojo Tokiyori and is considered to be one of the three early founders of the Soshu tradition there together with Ichimonji Sukezane and Awataguchi Kunitsuna. He is also said to have taught Shintogo Kunimitsu in Kyoto. His son succeeded as the second generation, and his grandson is thought to have continued the line in Bizen Province during the Nanbokucho era.
This is a fine and typical tachi by the smith, with the healthy fullness of body, elegant form, and the rich steel texture of a classic Bizen sword.