Manriki is a traditional Japanese throwing chain weapon, generally about 11 inches (280 mm) long. When used with a whipping motion of the wrist, it can injure or knock out opponents at a considerable distance. Some manriki are made with chains as long as 3–6 feet (0.91–1.8 m) with weights on the ends. They are common to the ninjutsu style. They are quite versatile weapons that are viable non-projectile weapons as well as projectile weapons. They are quite similar to the kobudo Surujin.
The chain is generally held concealed in the hand until the attacker approaches within distance. One of the weighted ends can then be launched at the opponent, or the defender can get in closer and use the weights at close range to punch and entangle the attacker in the chain.
The Manriki was very useful in direct combat against swords. It was strong enough to stop a slash from a sword blade when the ends were held in each hand and then tangle the arms and/or neck of the swordsman.
Its ability to be easily concealed in the hand or on the person made it a very popular weapon where a more obvious weapon may be forbidden. It was sometimes used by guards when they had to protect an area where the spilling of blood was forbidden. It also is extremely good at strengthening wrist muscles when used properly, and is sometimes used as a training device for martial artists. A modern, improvised equivalent is a chainlock.