三所物 Mitokoromono / Three Items

What is Mitokoromono in Japanese Katana terminology?

This refers to a set of three sword fittings: the Menuki (めぬき), the Kozuka (こづか), and the Kogai (こうがい). These three pieces are often made with the same materials and designs. Many of the Mitokoromono made during the Muromachi period were lost due to actual use, and many of the ones that remain are those that were matched with different fittings with the same design later on.