Gamaken

is a giant toad that first appeared in Part II. He wields a Sasumata-like weapon and a shield. He seemed to be a skilled fighter whilst fighting alongside Naruto. He also seems to be wearing the same robe as Gamabunta.

Personality
He is constantly referring to how clumsy he is (in the manga he refers to himself as weak insted), and constantly seems nervous, albeit he also says that he will do his best.

Hunt for Uchiha arc
He was first summoned by Jiraiya when he was facing the Akatsuki leader Pain and decided to use the Sage Mode. However, in order to use Sage Mode, it would take him some time to prepare it, and he could not afford to take the risk of leaving himself unprotected, so he summoned Gamaken. During the time it took for Jiraiya to prepare the technique, Gamaken was forced to face off with a great variety of Pain's animal summons, and was kicked back and forth throughout the tower they were in until he was pushed into a sewer, after which Jiraiya then told him to return as he had finally finished the preparation for his technique.

Invasion of Pain arc
Gamaken, along with Gamabunta and Gamahiro, were later summoned to assist in Naruto's fight with Pain. They combatted the various animals summoned by the Animal path until they were sent flying beyond Konoha's borders by the Deva path.