from web site
Some derive their name from the products they were fashioned from, such as kugi-gata (nail type), hari-gata (needle form) and tant-gata (knife kind); others are named after the object to which they appear comparable, such as hoko-gata (spear form), matsuba-gata (pine-needle type) while others were just named after the item that was tossed, such as kankyuto (piercing tool type), kunai-gata (utility tool type), or teppan (plate metal) and biao (pin).
The origins of the bo-shuriken in Japan are still uncertain in spite of continuing research study in this area. This is partially due to the fact that shurikenjutsu is a secretive art, and also to the fact that throughout early Japanese history there were in fact numerous independent innovators of the skill of tossing long, thin objects. The earliest recognized mention of a school teaching shurikenjutsu is Ganritsu Ryu, common during the 17th century.
Existing examples of blades utilized by this school appear to show a mix of an arrow's shape with that of a needle traditionally used in Japanese leatherwork and armor manufacture. There are also previously discusses in written records, such as the Osaka Gunki (, the military records of Osaka), of the standard knife and short sword being thrown in battle, and Miyamoto Musashi is said to have won a duel by tossing his brief sword at his challenger, killing him.