Hiruko

is a puppet used by Sasori. As a puppet, he serves as Sasori's "puppet armour", as Sasori is capable of hiding inside of it. Sasori even adorns Hiruko with the Akatsuki's robes, and hides inside it every so often that others come to recognize him only when he was wearing it. Hiruko is Sasori's puppet.

Abilities and Weapons
All weapons installed in Hiruko are coated in Sasori's special brand of poison, which kill the victim after three days of painful paralysis.
 * Extendable iron tail provided offence by stabbing and defence by rotating around the body.
 * Heavy back shell for additional defence.
 * Rapid launching of senbon from the mouth.
 * Torpedo-shaped left arm that launches shrapnel of senbon in all directions.
 * Grants Sasori a gruffer voice.

Trivia

 * can be translated to "leech child".
 * Hiruko is a Japanese Fisherman god. It can also be translated into "Ebisu".
 * Hiruko's tail was seen in a flashback of Sasori's childhoods as a part of an unfinished puppet. It had a split end.
 * Hiruko was erroneously called Sasori's eighteenth puppet in the anime. This was because literally translates to "number eighteen".