Like most swords, traditional Japanese swords were typically stored in a sheath. When the samurai warrior wasn't using his sword, he would keep it a sheath. This served several purposes, one of which was to protect the sword from damage. Without a sheath, swords were exposed to the elements and more likely to sustain damage.
Additionally, a sheath protected the samurai warrior from self-injury. When a sword was properly maintained, it would feature a razor-sharp edge that could easily cut into the skin. So, samurai warriors would carry their sword in a sheath to reduce the risk of self-injury.
Traditional Japanese swords were typically stored in one of two different types of sheaths: the shurasaya or the jindachi-zukuri.
To learn more about these sheaths and how they differ, keep reading.
Perhaps the most common type of sheath in which traditional Japanese swords were stored is the shirasaya. It was made of hand-carved wood with a curved shape to accommodate the katana's curved blade. A typical shirasaya featured two pieces that jointed together, one of which was longer than the other. The small piece could be removed by pulling up; thus, exposing the sword's hilt and allowing the samurai warrior to quickly draw the sword.
The shirasaya is a relatively simple, easy-to-produce sheath, making it an attractive choice for mass-production. And because it was made of wood, the shirasaya was often used for long-term storage. This is in stark contrast to the jindachi-zukuri, which we're about to explain.
A second type of sheath for traditional Japanese swords is the jindachi-zukuri. While the shirasaya was used primarily for long-term sword storage, the jindachi-zukuri was a more battle-ready sword sheath. It typically featured embellishments and decorations, and was worn either on the belt or by straps. When worn by straps, it was referred to as a tachi-style jindachi-zukuri.
The jindachi-zukuri was more difficult and time consuming to produce than its shirasaya counterpart. The individual making the jindachi-zukuri would often carve intricate details into the side.
Of course, there were other sheaths designed throughout feudal Japan. The shirasaya and jindachi-zukuri were simply the two most popular. The shirasaya was a more basic sheath used primarily for long-term storage, whereas the jindachi-zukuri was a battle-ready sheath with intricate decorations. Hopefully, this gives you a better understanding of the two primary sheaths used for traditional Japanese swords.