Sword Sheath

There are two types of sheaths:

One is the shirasaya. A shirasaya, is a plain wooden Japanese blade mount consisting of a saya (scabbard) and tsuka (hilt), used when a blade was not expected to see use for some time and needed to be stored. They were externally featureless save for the needed mekugi-ana to secure the nakago (tang), though sometimes sayagaki (blade information) was also present. The need for specialized storage is because prolonged koshirae mounting harmed the blade, owing to factors such as the lacquered wood retaining moisture and encouraging corrosion.

Such mountings are not intended for actual combat, as the lack of a tsuba (guard) and proper handle wrappings were deleterious; as such they would likely never make their way onto a battlefield.

The other one is the more decorative or battle-worthy sheath which is usually called either a jindachi-zukuri, if suspended from the obi (belt) by straps (tachi-style), or a buke-zukuri sheath if thrust through the obi (katana-style).