The ancestor of the modern kendo shinai is the fukuro-shinai (袋竹刀?), which is still in use in koryū kenjutsu. This is a length of bamboo, split multiple times on one end, and covered by a leather sleeve. This explains the name fukuro, which means bag, sack or pouch. Sometimes the older and rarer kanji tō (韜) is used, but has the same meaning as fukuro.
Some schools cover the entire bamboo in the sleeve and add a tsuba, like Kashima Shinden Jikishinkage-ryū does. In Shinkage-ryū, the sleeve is lacquered Kamakura Red, and rather than covering the entire length, is tied off at the non-split end. This particular kind of fukuro-shinai is also called a hikihada (蟇肌?), or toad-skin shinai. The name comes from how the leather looks after lacquering; the sleeves are actually made of cow or horse-hide.
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