Taiju Oki is a tall, muscular teenager with spiky brown hair, thick eyebrows, and distinctive vertical stone markings under his eyes, later replaced by identical war paint after his second revival. Orphaned young, he forged close childhood bonds with Senku Ishigami and Yuzuriha Ogawa, joining them in projects like launching knitted toys into near-space and crafting a swimsuit for Senku's adoptive father. Throughout high school, he exhibited remarkable stamina and endurance while strictly adhering to pacifism, never striking another person. On June 3, 2019, moments before confessing to Yuzuriha, a global petrification event turned humanity to stone. Sustained solely by his determination to profess his love, Taiju remained conscious for the entire 3,700-year petrification. Depetrified on October 5, 5738, he reunited with Senku, who revived six months earlier. Together, they developed nital, the revival fluid, successfully reviving Yuzuriha and Tsukasa Shishio. Taiju prioritized Yuzuriha's dignity by clothing her statue beforehand and postponed his confession to avoid pressuring her in their depopulated world. Taiju possesses immense physical capabilities: superhuman strength to hurl boulders and restrain powerful foes, endurance to withstand attacks from Tsukasa and others, and stamina allowing him to traverse 80 kilometers in five hours or perform repetitive underwater statue retrievals without oxygen. His mental resilience kept him aware during both petrification periods. While academically unintelligent—suggesting cellphones as civilization's most vital tool or misidentifying calcium carbonate sources—he displayed practical problem-solving, proposing grape wine for nitric acid distillation and recalling applications like powdered shells for soil fertilization. He also proved adept at deception while masquerading as a scientist. After Tsukasa's ideological split with Senku, Taiju and Yuzuriha infiltrated the Tsukasa Empire as spies. Following the factions' merger into the Kingdom of Science, Taiju led its Farming Division and contributed to the Power Team. He participated in expeditions to Treasure Island and America, enduring a second global petrification. During the subsequent seven-year petrification timeskip, he again maintained consciousness. Revived, he resumed agricultural duties and supported the moon-landing project, eventually marrying Yuzuriha. On later missions, he assisted mining operations at Superalloy City, reviving and collaborating with former adversary Maya Biggs, establishing mutual respect. Taiju's defining trait is loyalty. He trusts Senku implicitly, sacrificing himself to lions for his friend's escape and supporting his plans without question. His devotion to Yuzuriha motivates his actions, from shielding her during petrification to protecting her in conflicts. Despite his pacifism, he confronts threats nonviolently, offering himself as a target to deter Tsukasa from destroying statues.