Ibuse

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

Background
Ibuse took part in Hanzō's fight with Jiraiya, Orochimaru and Tsunade. He has also fought against Chiyo numerous times, alongside Hanzō.

Abilities
Ibuse was a powerful summon, shown from his participation in combat against several powerful shinobi and emerging unharmed. In the anime, Ibuse has shown a great amount of raw strength, being capable of easily toppling trees with a single leg.

Poison
Ibuse was able to release a Poison Mist from his mouth, which was 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 with the correct antidote. The poison must first be generated and then stored for a total of five minutes within Ibuse's body before it can be expelled again.

Ibuse was also capable of concealing himself and navigating underground. He could then resurface beneath Hanzō's enemies and swallow them, trapping them in his mouth until they have succumbed to the fatal effects of the poison.

Fourth Shinobi World War: Confrontation
While pursuing the Surprise Attack Division, Hanzō summoned Ibuse, who immediately exhaled a large quantity of poison in order to immobilise the fleeing shinobi. Hanzō then leaped off of Ibuse to finish them off but they are saved by a group of samurai. Chiyo then divulged to Kankurō and the samurai that Ibuse's poison needed at least five minutes to replenish. Because of this, Hanzō ordered him to hide underground. He later emerged beneath Mifune, swallowing him in an attempt to kill the samurai; however, Mifune slashed through Ibuse's head and escaped, presumably killing him in the process.

Trivia

 * Despite initially portrayed as being green in colour, during Ibuse's later appearance in the anime, he is depicted as being a brown colour.