Yo Uei served as a police officer pre-petrification, gaining notoriety for employing excessive force against fleeing suspects, a tendency that hindered his career advancement. Petrification struck him mid-urination against a wall. Revived by Tsukasa Shishio, he enlisted in the Empire of Might as an enforcer. Tasked with guarding Chrome during the Stone Wars, he abandoned his post after Chrome's escape, fleeing the empire to evade punishment and instructing subordinates to falsely report his death for their protection. While hiding near Ishigami Village, he encountered Homura, freeing her upon her promise of future benefits. Discovering the empire's merger with Senku's Kingdom of Science, he feigned amnesia to join them, aiding Yuzuriha in statue restoration. He participated in the Kingdom's shipbuilding contest, producing only a poor raft. Envy grew towards Ryusui's lifestyle, and he initially dismissed the new currency until understanding its value, subsequently being manipulated into labor by Senku and Gen. During hot air balloon construction, he clashed with Magma over sewing techniques and failed to secure a balloon seat in Gen's lottery. For farming, Gen pitted him against Magma in competition; both failed initially until adopting Taiju's soil improvement methods. On the voyage to Treasure Island, Yo suffered severe seasickness, relieved by Senku's remedy. After Kirisame, acting on Ibara's orders, petrified the crew, his statue was discarded into the bay. Recovered by Ryusui's team, he was revived when the Kingdom required firearms expertise. Tempted by the gun's power, he was swayed by Gen's flattering suggestion he become the stone world's sheriff and encouraged by Amaryllis's flirtation. Despite poor initial marksmanship, he practiced secretly. During battle, he missed shooting Moz and was knocked overboard. With his last bullet, he shot the petrification device from Ibara's hand but was immediately petrified by Ibara. Revived post-battle, he later pointed his gun at Tsukasa upon his revival, though tensions eased as Tsukasa addressed new threats. Traveling to America, Yo lost money betting on Ryusui during poker and complained about alcohol scarcity until beer's recreation, drunkenly recounting his fight with Ibara. Upon arrival, he joined the warrior team escorting explorers, expressing excitement when alligators attacked, craving meat. During an aerial assault, he fired at an enemy plane despite Hyoga deeming it futile. Magma manipulated him into a reckless attack plan, thwarted by Nikki. He later ogled Luna and commented on Senku's preference for blondes. Ryusui confiscated his gun during air combat. Stanley's forces eventually captured and subdued him. In South America, Yo expressed skepticism about diamond creation but became invested in the process, wishing he had met Senku earlier for wealth creation. He fought American soldiers over the petrification device. When Magma misstated the device's activation range, Yo called him an idiot, prompting Nikki to call Yo dumb in return. Shot in the torso during the conflict, Nikki urged him to continue, assuring him the injury was non-fatal if petrification succeeded. He was petrified during Joel's activation of the device. Revived nine years later in Corn City, Yo joined the computer construction effort, expressing frustration with the labor and mocking a math contest until Minami revealed a monetary prize. He later pocketed earnings from the new banking system. He and Ukyo delivered corn and the petrification device to Senku's team in Australia. In Indonesia, he participated in rice farming without complaint due to personal interest. Returning to Japan, he approved villagers' dam construction work and fed Suika's pets, prompting them to stay. He joined the village feast before being petrified again during the Moon Mission arc. Physically lean and muscular with spiky auburn hair, Yo often wears a stone eyepiece over his right eye. His standard attire included a gray sleeveless yukata, a large left shoulder pad, spiked necklace, and ankle bracelets. Post-revival, he wore shoulder pads bearing the Kingdom of Science insignia. His personality blends abrasiveness, arrogance, and cowardice. He frequently belittled others, particularly stone-world humans, considering modern humans superior. He avoided difficult work unless motivated by profit or power. Despite his flaws, he demonstrated loyalty to the Kingdom of Science after the alliance and occasionally showed concern for subordinates. His abilities, stemming from police training, include tonfa proficiency, marksmanship (though initially rusty), and running speed. His statistics are power 3/5, speed 4/5, technique 5/5, and reach 1/5. He holds the record for most petrifications.