In the Naruto series, Ōnoki, the third Tsuchikage from Iwagakure, is one of the most complex characters. A lovable old man at times that complains way too much about his back problems, he's a deceptively fearsome warrior and one of the best Kages (village leaders) of all time.
However, with the Boruto franchise bringing his former accomplice, the sinister Doctor, back into play, let's look at how the heroic Ōnoki fell from grace in a tale filled with grief and tragedy.
Ōnoki was one of the leaders who didn't trust the other Great Nations before Naruto's time. He even fought Madara Uchiha and realized Konoha had evil methods of subjugating rivals. As he got older, not even Hiruzen (the Third Hokage) was someone he'd trust, which is why Ōnoki kept Iwa isolated and always on the verge of going to war. It got so bad, in fact, that he'd even hire the Akatsuki at times, not knowing they were Madara's puppets.
But when Madara and Obito revealed their true plan to conquer the world via the Infinite Tsukuyomi and place everyone in a dream world, he had no choice but to ally with all the other Kages. He put aside differences, especially with the Raikage, and inspired by Naruto, Ōnoki would become one of the alliance's most important players. He defended them from certain death on quite a few occasions, using his Dust, Earth and Fire Release techniques to stave off Madara's meteor showers, although his body kept weakening. It culminated in Tsunade trying to heal him, but ultimately, they all got stuck in the dream world until Naruto and Sasuke saved them. But while many thought this would lead him to retire and enjoy a new era of peace, it proved to be Ōnoki's undoing.
Mini-wars still occurred and he lost his grandson, Kozuchi, to some rogue ninjas, motivating him to develop an army outside of the alliance's rules. Ōnoki believed society needed soldiers who weren't human and that's why he began creating synthetic warriors. However, his successor and granddaughter Kurotsuchi rebuffed these abominations as they were uncontrollable, which led to him working on his own. That is until the Doctor approached him with the White Zetsu -- soldiers Madara used that had Hashirama, the First Hokage's DNA, in them. At this point, Ōnoki, who many thought to be senile, was lost to the darkness, becoming the very monster he fought against; one that reeked of sinister scientists such as the sneaky Orochimaru and Kabuto.
What made it worse was the Doctor kidnapped Mitsuki, an Orochimaru clone, all to perfect the creation of Ōnoki's army. The seasoned war vet came to rue all this when the creations, aka the Fabrications and the Akuta, turned on Iwa, staging a coup led by a clone of Ōnoki called Kū. He treated Kū like a son but in actuality, Kū was all his anger and grief bottled up into one vessel. The vet told Boruto he was trying to protect the future so no child soldiers would die but Boruto made a salient point that these beings have souls too, so treating them like mindless objects just wasn't right. By the time they turned on Ōnoki, it felt like his comeuppance. He's reaped what he sowed for not believing in progress, evolution and Naruto's alliance, and Kū was a dark reflection of that.
Ōnoki thought peace made them weak but thanks to Boruto he remembered the truth: there was indeed strength in numbers. Ōnoki would return to his old ways, helping fight off his creations, only to die after the war with Kū took a major toll on his frail body. He died a heroic death, saving Boruto and Co. as he regained hope; but still, it could have been avoided if he wasn't so cynical.
Ōnoki's funeral was subsequently covered-up as Naruto hid how he became a traitor. He just couldn't out an 'uncle' like that, and so the alliance lied about it being health-related. Sadly, Boruto couldn't attend the funeral but he knew Ōnoki deserved to see happier days. He was simply trying to protect everyone and now, his research appears to have fallen into Victor and Kara's hands. Thanks to the Doctor, Ōnoki's legacy could still be sullied if all this becomes public, creating tension within the shinobi coalition just like in the old days.
