“Three throwing stars that can be hurled at zombies, dealing PHYSICAL damage.”
Shurikens are a Curveball featured in Dead Island 2. They function very similarly to the variants of the Throwing Knife from Dead Island: Riptide.
Shurikens are unlocked after collecting the Shuriken stuck in the car directly in front of the travel point outside of the Halperin Hotel. When used, three Shurikens will be thrown, damaging any zombie in their path. Should a Shuriken hit a limb, it be severed.