Bungo Sadahide
定秀 (Sadahide)
A monk-smith of Bungo, between the end of the Heian and the Kamakura period; one theory makes him the master of Yukihira.
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Sadahide, whose name Kotobank reads Jōshū, was a monk who forged in Bungo province; tradition links him with Mount Hikosan, in Buzen. The sources place him between the end of the Heian and the Kamakura period, without firm dates. His signature «Bungo no kuni Sō Sadahide» survives, in which sō (僧) means monk.
According to a theory that the same dictionary records, he was the master of Yukihira, the Bungo smith of the same period; this is a tradition, not a documented fact. The Kotō Taikan reproduces two blades with his signature.