The Japanese word for the scabbard of a sword or knife is saya. As a category of objects, they are often called yari saya, yarizaya or yarisaya, since yari is the name of a particular type of spear with a very long shaft.
These yari were used to dramatic effect during the long processions undertaken by the local daimyō as required by the Tokugawa shogun during the sankin kotai, when they would repeatedly move from their estates to the capital of Edo and back again. In the illustration above, the samurai can be seen holding their spears aloft with a variety of saya shapes. As I find more pictorial examples of the use of saya, I’ll post them on this page.
Feudal procession entering Edo,1889, by Ginko (active 1874-1897)
Japanese Scabbards for Spears in the Edo Period
Published 1996, 102 pp., 8.25" by 8.5"
The first and only book to be written about Japanese saya, chock full with color photographs of a tremendous variety of saya. The author observes that the Japanese have yet to consider these wonderful objects as collectible in their own right; the same could also said about most collectors in the West. An inspiring introduction to saya, alas, it is in Japanese.