Saya

A saya (鞘) is a slim wooden cover, usually magnolia, that slides over the blade and is held in place by a small pin or friction. It keeps the edge from knocking against other things in a drawer or a knife roll, and it protects your hands when you reach past the knife. Sayas are often sold to fit a specific blade shape and length, so a santoku saya will not fit a longer gyuto. They are the gentlest way to store a Japanese knife loose, but the blade must be completely dry before it goes in, since a damp blade in a snug wooden sheath is an easy way to start rust.