The shuriken (hidden blade) was a very effective weapon used primarily by Ninja (Spirit Warriors). Spirit warriors concealed these thin steel plates in the pockets of their uniforms and belts and threw these projectiles at their enemies. Even though the Ninja primarily used shuriken to distract their enemies to set up a quick counterattack, a small cut or laceration from a shuriken could be fatal. This was due to the fact that some Ninja dipped their shuriken in poison, animal feces, or paralyzation liquids.
Dr. David Jackson- 5th Degree Black Belt, demonstrates how to throw one, two, and three shurikens at a target in the video below. Aiki-Karate Black belts are required to throw 10 shurikens (five in each hand) as part of a Shuriken-Jutsu technique.
Amazon.com has a wide variety of shurikens available that Aiki-Karate students utilize. Here are a few student favorites: