Ōnoki

is the, and the leader of Iwagakure. He is called. He is the oldest Kage at the Kage Summit.

Background
At some time in the past, Ōnoki fought with Madara Uchiha, the only living Kage to do so. He hired Akatsuki many times for their services. He has also apparently known A, the Fourth Raikage, since the latter was young.

Appearance
Ōnoki is an old man with a size of one and half times his head piece. His facial features include a triangular beard and a mustache with angular corners. He has a big red nose and thick eyebrows (similar to those of Rock Lee). The top of his head is completely bald, although, he has some hair at the back and sides of his head, the back of which is tied with a yellow ribbon into a ponytail. All of his hair (ponytail, sideburns, facial) is white.

Personality
Ōnoki is very proud but appears frail, with constant complaints referring to his hips and back. He also refuses to retire and choose a successor as Tsuchikage despite his frailness, and insisting that he is plenty strong to continue to rule the village. Kurotsuchi describes him as a "stubborn old man." His pride has him give very little respect for those younger than him, as he verbally attacked Gaara, who is many years younger, on numerous occasions. He also seems to be quite ruthless, taking down a heavily-injured Sasuke, who just finished fighting three other Kage before him, on the claim that everyone else there wants Sasuke dead even though Ōnoki himself has no grudge against Sasuke personally, and then immediately turning his attention to a devastated Karin, claiming that she's next to die. He does, however, seem to be considerate enough to let Madara speak for his actions, reasoning with the Raikage to listen to his reasons before their actions first before making their own. According to his thinking of strategy, Ōnoki might be the type of person who takes risks. A similarity can be shown with Tsunade, as she has a habit of gambling and taking risks often. Remembering what Gaara said to him, he states to Akatsuchi and Kurotsuchi that he remembered what he really used to be before he became a stubborn old man, possibly meaning he had a more kind and friendly heart in his youth.

Abilities
Despite being physically frail, he seems to be both knowledgeable and confident in his ninjutsu skills. Ōnoki's Dust Release ninjutsu allow him to pulverize his enemies to molecule-sized dust. He is also skilled with Earth Release ninjutsu and has shown the ability to levitate.

Five Kage Summit arc
When Ōnoki set out for the Kage summit, the villagers of Iwagakure encouraged him to show the other Kage how strong he was, though his bodyguards Akatsuchi and Kurotsuchi were less enthusiastic. He ended up hurting his hips, and had to be carried to the meeting. When they arrived in the Land of Iron, Ōnoki explained to Akatsuchi about the samurai.

When the Summit began, Ōnoki expressed his concern that Akatsuki could capture the jinchūriki so easily, considering it an embarrassment. When the Raikage ridiculed him for employing Akatsuki in the past, Ōnoki defended Iwagakure's actions and instead blamed Kumogakure for increasing its armaments in times of peace. Mifune then suggested that the five Kage join forces against Akatsuki, and nominated Danzō as the group's leader. Ōnoki was outraged by the suggestion, but Mifune pointed out that he was too old and had made too much use of Akatsuki in the past to be trustworthy.

When the Kage were alerted to Sasuke Uchiha's presence and the Raikage went off to confront him, Ōnoki commented that he was still as reckless as an adult as when he was young. While waiting for the Raikage's return, he offered to give Gaara tips on how to be a good Kage, having previously dismissed Gaara's suggestions on the basis that he was too young. Gaara only asked why he has no faith.

Sasuke arrived at their location soon after, but Ōnoki chose to let Mei Terumī deal with him. After Sasuke proved able to evade her attacks, he decided to intervene, attacking Sasuke with Dust Release: Detachment of the Primitive World Technique. He then turned his sights to the devastated Karin. Although Ōnoki believed he had turned Sasuke to dust, Madara Uchiha appeared with Sasuke in tow. Madara sent Sasuke away and told the Kage of his Eye of the Moon Plan. Madara concluded by requesting that the two remaining jinchūriki be given to him. Ōnoki and the other Kage refused, beginning the Fourth Great Shinobi World War.

With war declared, Ōnoki, Gaara, Mifune, Mei, and the Raikage agreed to form a coalition against Madara and the Akatsuki. The group was mistrustful of the Hokage, so Ōnoki agreed to seek Konohagakure's assistance by approaching Kakashi Hatake. In terms of tactics for the forthcoming battles, Ōnoki suggested they use their two remaining jinchūriki to their advantage, but the other Kage disagreed, believing that would make them too easy to be captured.

After it was decided that the Raikage would lead the ninja alliance, he asked Ōnoki to reveal all the knowledge he had on Madara as he once fought him. When the meeting ended, Ōnoki surprised his men by not deciding to simply kill the jinchūriki. When asked why, he merely stated that it was because he remembered who he was "Before he became a hard-headed old man", referring back to how Gaara talked down on him about "losing himself."

Quotes

 * (To Akatsuchi)
 * (To the Fourth Raikage)
 * (To Kurotsuchi)

Trivia

 * The word "Ryōtenbin" literally means "two alternatives"; this may be why the Viz translation has Ōnoki calling himself, "...the great Fence-Sitter of Iwagakure!"