A kusarigama is a weapon that was used a long time ago in Japan. It's made up of two parts: a long chain and a sharp and pointy ball or blade that's attached to the end of the chain. The chain is usually about as long as a grown-up's arm.
When you use a kusarigama, you swing the ball or blade at your enemy while holding onto the other end of the chain. You can also use the chain to trip up your enemy or to pull yourself closer to your enemy. This makes it a very tricky weapon to fight against.
Using a kusarigama takes a lot of practice and skill because you have to be really good at swinging and balancing the chain and timing your attacks just right. It's not a toy or something you should try to use on your own without an expert to help you.