Ōnoki, also known as Ōnoki of Both Scales, was the Third Tsuchikage of Iwagakure, the Hidden Stone Village of the Land of Earth. He was a short, elderly man, standing roughly 130 centimeters tall, with a large rounded nose, deep-set eyes, and a thick white beard and moustache. He typically wore the full ceremonial robes of a Kage and the tall conical hat bearing the kanji for earth, and his age was evident in his stooped posture and wrinkled skin. Despite his small stature and advanced years, he was regarded as one of the most formidable shinobi of his era and held the longest tenure among the Kage active during the main events of Naruto Shippūden.

Ōnoki was the grandson of the First Tsuchikage and the student of the Second Tsuchikage Mū, from whom he inherited the secrets of Dust Release. Born during the era when the hidden villages were first established, he lived through the Second and Third Great Ninja Wars and was among the few survivors of direct combat with Uchiha Madara. As a youth of about thirteen, he fought Madara alongside Mū and was overwhelmingly defeated, an experience that left a lasting mark on his worldview and shaped much of his later conduct.

In personality, Ōnoki was proud, headstrong, and boastful. He stubbornly refused to retire or name a successor, insisting that he was still strong enough to lead his village, and he frequently complained about the lower back pain that plagued him in his old age. His pride made him dismissive of those younger than himself, and he often belittled Gaara, treating the young Kazekage's idealism as naivety. He was blunt, sarcastic, and at times ruthless, as shown during the Five Kage Summit when he attacked a gravely wounded Sasuke Uchiha and threatened Karin, acting on the belief that the ninja world wanted Sasuke dead even though he held no personal grudge.

His motivations were rooted in protecting Iwagakure's interests and maintaining its military standing. This pragmatism led him to hire the Akatsuki as mercenaries in the past, a decision he justified through his concern over the growing militarization of Kumogakure. Beneath his cynical exterior, however, he carried guilt over choices he had made, including having refused to send aid to Sunagakure during a crisis years earlier. He openly admitted that his encounters with Madara in his youth had caused him to lose sight of who he truly was before he became a hardened old man.

Ōnoki's role in the story grew considerably during the Fourth Great Ninja War. At first he resisted the proposal to form an Allied Shinobi Forces, distrusting old enemies and viewing alliances as temporary conveniences, but the sincerity of Gaara's words reminded him of his former self, and he became a committed supporter of unity among the villages. He went on to serve as one of the supreme commanders of the Allied Shinobi Forces, fighting the reanimated Second Tsuchikage Mū alongside Naruto Uzumaki, defeating the Second Mizukage in cooperation with Gaara, and joining the other four Kage in their desperate battle against the reanimated Madara Uchiha. Later he also took part in the effort to extract the tailed beasts from Obito Uchiha.

His key relationships reflected both his personal history and his growth. He was the father of Kitsuchi and the grandfather of Kurotsuchi, who would eventually succeed him as the Fourth Tsuchikage, and he tolerated his granddaughter's blunt criticism with a degree of amusement. He had known the Fourth Raikage, A, since the Raikage was young, and during the war he worked alongside him, even freeing him from a genjutsu. He had also been a teacher to Deidara, whose explosive art and rebellious ways irritated him, though he remained quietly proud of his former student and did not hesitate to mock Deidara's defeat by Sasuke. His most significant development came through his interactions with Gaara, whose willingness to forgive forced Ōnoki to confront his own cynicism and helped restore his belief in cooperation.

In terms of abilities, Ōnoki was a master of Dust Release, a rare kekkei tōta formed by combining earth, wind, and fire nature transformations. His signature technique, Dust Release: Detachment of the Primitive World Technique, created a transparent cubic or conical barrier that disintegrated anything inside it at the molecular level, leaving no trace, and its power was reputedly enough to destroy an entire island. He could alter the shape and size of the technique, and his enhanced Boundary Detachment variant was capable of erasing the Susanoo of Madara's twenty-five wood clones in a single blast. He also displayed extensive mastery of Earth Release, including the ability to form rock fists, summon massive stone golems, create rock clones and protective rock arms, and raise or lower sections of terrain. His most distinctive specialty was weight manipulation, which allowed him to reduce the weight of objects and people so drastically that he and others could fly at high speed, or increase weight to immobilize enemies and amplify the force of attacks. He applied these techniques to allies as well, lightening Gaara's sand and the Fourth Raikage's body, and even carrying the giant Island Turtle through the air. In addition, he was skilled enough to break genjutsu, as he demonstrated when he released the illusion placed on the Fourth Raikage.

After the war, Ōnoki eventually stepped down and was succeeded by Kurotsuchi, though he continued to live on into the era of his grandson Naruto's adulthood. In his final years he confronted the threat of Kū, and after destroying Kū with Dust Release he exhausted himself and died, ending the long life of a man who had carried the burdens of his village and his past across more than seventy years of shinobi history.