The kusari fundo- three foot weighted chain is one of the historical training tools that we practice with in our martial art.
As a historical training tool used by the samurai of Japan, what relevance does it have, if any to the here-and-now of today?
Similar to all of our training tools- the spear, sword, and sticks, each one is a way to understand certain laws of distance and timing.
Each tool operates at a fixed length, and being able to use it correctly at that length teaches about that distance and timing, making it easier to see in unarmed taijutsu movement.
The kusari fundo works at three feet or less- three feet when extended, and less if the chain is shortened while in use, or with the weights in hand.
Another unique property of it, is the ability to use the flexibility of the chain itself- rigid or fluid through the use of body postures- kamae.
In this way the kusari fundo has a number of unique movements to offer and explore.
Historical training tools are just hat- historical and should never be used in modern training scenarios, unless they are safe foam versions of the training tool, and under the direct supervision of a martial arts teacher.