When he was an adolescent, Ōnoki was tasked with cleaning his village's Stone Monument. As he did so, the First Tsuchikage came and spoke with him. Ōnoki, who believed that the First was just a cheap old man to have such a simple thing as the symbol of the village, was then told that the stone represented the unmovable will of the shinobi of the village. The First then told Ōnoki that he too possessed that strong will, but would lose it if he didn't face adversities with determination.
As a young man, Ōnoki was a student to the Second Tsuchikage, Mū who passed down to him the secrets of Dust Release techniques, and eventually, the title of Tsuchikage. At some time in the past, Ōnoki fought with Madara Uchiha, and is the only living Kage to do so.
Several Ages Ago, The Two Tailed Bunnny appeared and ravaged the Hidden Rock Village. The Eighth Tsuchikage defeated the Bunny by sealing it's spirit into the Newborn Mizuichi. His Parents was pierced to protected him from the dragoon tail that pierces buildings and burns it. Onoki the Third Tsuchikage was seen as he saw Mizuichi's Parents placing a newborn child version of Mizuichi and places the basket on the river and floats away to Izumo.