One of the traditional training tools in the Japanese martial arts, and of the historical samurai was the kusari fundo, also known as the manriki gusari: a weighted chain.
Consisting of a length of forged chain and two weights at the end it was used against the samurai sword (muto dori) and as a way to restrain people.
Many schools of use evolved from the tool, each with a slightly different length or shape of the attached weights. Some of the weight are smooth, others round or octagon.
Each school (ryu) of the chain had its own secret reason behind the construction.
With regard to the chain, the length was usually fixed around three feet in length for balance and distance. One needed to be able to manipulate it for the various techniques (waza) and the longer the chain the harder it could be to use, while at the same time being a solid distance to use against a sword or bladed weapon- which is about 3 feet in length and distance, equaling six feet- three for the chain and three for the footwork.
Before we begin to explore some of the training movements with the kusari fundo it is important to realize this is a historical martial arts training tool.
A real chain with weights should never be used in training either partnered or solo as the risk for permanent injury is great. There is zero reason to use or own a real kusari fundo.
Padded and rope training versions are available or easily made, and even these need to be approached with caution.
Training with the kusari fundo begins with kamae- body postures and ways of holding the chain so it can be swung and manipulated. Key with these postures are the ability to move both the chain and the feet at the same time- they are linked in movement in regard to timing so one does not hit oneself with the weighted chain.
Side, overhead, up, and down- happo all directions.
There is also training where the kusari fund is folded up and held in the hand concealed, followed by being cast out at the training partner, along with the weight being used as a fist load.
After exploring the various kamae the next training step is the ability to catch limbs with the chain and take control of your training partner’s body.
Wrapping limbs with the chain and using that to guide into various locks, throws, and restraints while also using the weights.
Over time the kusari fundo becomes an extension of distance, allowing one to work at a further distance vs. just using your hands. It also wraps, snarls, and restrains your training partner, locking various points of movement so they are unable to take ukemi.