Taiju Ōki, a towering Japanese high school student orphaned in childhood, forged deep bonds with Senku Ishigami and Yuzuriha Ogawa. He joined their science experiments, including rocket-building and crafting a swimsuit for Senku's astronaut father. For five years, he silently cherished Yuzuriha. On the very day in 2019 he resolved to confess, a global petrification event transformed all humans to stone. Conscious for 3,700 years within his stone prison through sheer willpower and his vow to confess to Yuzuriha, Taiju revived on October 5, 5738, into a world reclaimed by nature. Discovering Yuzuriha's statue protected beneath a tree, he followed Senku's carved message downstream to reunite. Senku utilized Taiju's immense physical strength for demanding tasks like foraging and gathering resources. During one forage, Taiju's discovery of wild grapes and suggestion to ferment wine proved crucial, enabling Senku to create nital, the revival fluid. Taiju insisted on clothing Yuzuriha's statue before revival to protect her dignity. Standing 6'2" with a muscular build, Taiju possesses spiky brown hair, thick V-shaped eyebrows, and brown eyes. Initial stone markings – a longer one under his left eye and a shorter under his right – faded after his second depetrification, though he later repainted them. He typically wears a sleeveless knee-length cloak tied with a rope and primitive boots. Taiju radiates unwavering enthusiasm, kindness, and loud expressiveness. Despite his energy, he maintains exceptional emotional control, adhering strictly to pacifism. He refused to retaliate against Tsukasa Shishio even after Tsukasa fatally injured Senku, offering to endure beatings to prevent statue destruction. His fierce loyalty drives him to risk his life for Senku and Yuzuriha. Though academically challenged – proposing sourcing materials from long-gone locations – he shows practical resourcefulness, like applying Senku's lesson about seashell fertilizer to boost crops. He memorized subtle cues like Senku's neck-cracking code, successfully impersonating a scientist to deceive enemies. His physical capabilities are immense: stamina allowing an 80-kilometer run in five hours and repeated deep dives without oxygen tanks, strength sufficient to hurl explosion-triggering boulders or restrain fighters like Oarashi, and endurance enabling him to withstand kicks from Tsukasa and judo strikes without immediate collapse. His mental resilience kept him conscious during both petrification events. Under Senku's direction, Taiju and Yuzuriha infiltrated the Tsukasa Empire as spies. After factions merged into the Kingdom of Science, Taiju led the Farming Division and joined the Power Team. He participated in expeditions to Treasure Island and America, enduring a second global petrification. Following a seven-year timeskip, he resumed duties for the moon mission and married Yuzuriha.