Identify your kunai. Ninjas use several variations, and it is important to identify your kunai in order to implement its use successfully. Two types of kunai knives exist: large ones, used for thrusting and stabbing, and small ones, used for throwing. All other variations concern types of blade. If your knife's blade is 4 to 5 1/2 inches long or roughly the same size as your extended hand, it is a throwing kunai. If the blade is longer, it is a thrusting kunai.
Thrust your kunai. A thrusting kunai is used very much like a dagger. Because the kunai does not have a guard, the most effective way to hold it is to wrap your hand around its hilt by making a fist. Find a stable stance, and commence to make short sharp jabs at the object you wish to stab, such as a medium-sized cardboard box.
Throw your kunai. A throwing kunai is used much like a throwing star. Get into a stable stance in order to project your kunai accurately. This can be done by leaning one foot forward and slightly bending your leg. After this, make an L shape with your finger and thumb while holding your arm back. Hold the dagger facing down by the handle. With a quick gesture, move your arm down. Do not move your wrist because it is your arm's force that will project the dagger.