Mark with Japanese mark: 武州住　正恒 "Bushuu ju | #433372

武州住　正恒 "Bushuu ju Masatsune". This mark comes from a "tsuba", a sword guard designed to protect the hand from contact with the blade and an opposing sword. It was made by Masatsune, who worked as a "soukenkinkou" in the Nara line of the Ito house. Soukenkinkou is the Japanese name for metalworkers who design accessories for bladed weapons.