Menuki

Menuki are sword parts usually under the handle wrap on either side of the handle (tsuka) .  Originally, They were structural, keeping the handle connected to the sword.  Overtime, that functionality stopped & they became mostly decorative outside if helping maintain the sword grip.  They come in all different shapes, sizes and designs.  They are usually constructed from some type of metal or metal alloy.  Inlays or overlays of gold, silver & shakudo are very common. Menuki can be exact copies of each other, left/right copies, or complimentary designs which maybe of 2 different items.  For example, one menuki can be a mantis while the other is a grasshopper.   Here are some menuki examples with the mantis theme.