Kusarigama (鎖鎌) literally means "chain scythe". It is a variation of the gama (鎌), a scythe-like weapon that was likely inspired by farming tools. The kusarigama adds a chain to either the back of the blade or the end of the handle (like on this example). The idea was to hit or entangle the opponent with the weight and chain and follow up with an attack of the scythe blade.
A rather nicely made kusarigama. Scythe signed 則光作, "Made by Norimitsu".
Weight marked with the 10th year of Eishō, corresponding to 1514 A.D.
Sold by Mandarin Mansion in 2018.
The weapon is thought to have been developed in the Muromachi period (1336 - 1573). According to a 1776 account, legendary Japanese swordfighter Miyamoto Musashi fought and killed Shishido Nanigashi, who was believed to be a kusarigama practitioner but the account may be fictional.1
1. Nitenki (二天記), 1776.