Ibuse

is a poison salamander and Hanzō's signature summon. It was large enough for its summoner to stand on top of its head and when battling alongside Ibuse, Hanzō was powerful enough to fight, and eventually overpower all three of the Sannin.

Abilities
This salamander is able to release a Poison Mist from its mouth, which is capable of making the entirety of a victim's body numb just moments after inhalation and may eventually prove fatal, although these effects can be counteracted by the correct application of an antidote. The poison involved must first be generated and then stored for a total of five minutes within Ibuse's body before it can be expelled again.

Despite its large size, Ibuse is not only capable of easily concealing itself and navigating underground, but also emerging at a precise destination defined by Hanzō without any prior indication. This natural trait is often used in conjunction with its lethal poison, where after previously swallowing an unaware enemy by appearing directly beneath them suddenly, Ibuse confines them within its body until they succumb to the fatal effects of the poison.

Shinobi World War Arc
During the pursuit of various members of the Surprise Attack Division, Hanzō summons Ibuse, who immediately exhales a large quantity of poison in order to immbolize the fleeing shinobi. However, with Chiyo divulging the secrets behind this technique to Kankurō and the recently arrived support, Hanzō orders Ibuse to retreat underground. During its master's fierce confrontation with Mifune, Ibuse was then commanded to swallow the latter in an attempt to kill the samurai. However, Mifune managed to slash through the entirety of the creature's enormous head, killing Ibuse in the process.