manriki-gusari; weighted chain
A traditional Japanese martial arts weapon consisting of a chain with weights at both ends, used by ninja and in some classical martial arts.
The manriki-gusari is known as one of the ninja's weapons.
The name 万力鎖 literally means 'ten-thousand-power chain', reflecting its perceived effectiveness. The exact historical origin is uncertain, but it is associated with ninja and classical martial arts traditions.