The collar around the blade above the tang to fit the blade securely into the scabbard.

One or two piece blade collar around the Nakago, above the tsuba, used to secure the blade into the scabbard. Sets securely into the notches of the Ha and Mune-Machi's. Made from a variety of metals, usually copper, and sometimes gold-plated.

The blade collar on a Japanese sword.

a mandatory part