In Japanese, Kusari means chain. It is a very rare tool for a shinobi to use, but there have been 5 people who used it: Tobi, Kakashi Hatake, Izumo Kamizuki, Kotetsu Hanage, and Tayuya.
Used by Tobi
Tobi used a Kusari once against his battle against Minato Namikaze. During that time, Naruto Uzumaki was just born, and Tobi was wearing an orange mask with black flame patterns on it. When he fought Minato, in the middle of the fight, he used a chain that came from his sleeves.
Used by Kakashi Hatake
Kakashi Hatake used a Kusari once when he fought against Tendou Pein. He came out from underground and had planted chains before. Then he uses the chains to tie Pein up so he could destroy him with a Raikiri.
Used by Tayuya
Tayuya has a Genjutsu that includes chains in the illusion. She used it in her Cursed Seal Second Stage Mode in her battle against Shikamaru Nara. In the Genjutsu, Shikamaru was tied up in chains, and Tayuya used her flute in order to attack him.