Kusari-Fundo is a type of weapon that comes from Japan. It is made of a long chain with a weight at the end, kind of like a necklace. The chain is usually about the length of a tall person's arm, and the weight is about the size of a baseball.
When you use the Kusari-Fundo, you hold on to one end of the chain and swing the weight around. The weight can fly through the air and hit things like a hammer.
The Kusari-Fundo was originally used by samurais, who were like warrior knights in Japan a long time ago. They used it for self-defense and in battles.
But, it's important to remember that the Kusari-Fundo is a dangerous weapon and should only be used by trained professionals. It's not something that you should play with like a toy.