Ryusui Nanami, heir to the Nanami Conglomerate fortune, cultivated a childhood obsession with ships and navigation, constructing intricate models before commanding real vessels funded by a diminished million-yen allowance following clashes with his father over his maritime ambitions. His shrewd investments and competitive triumphs in ventures like dodgeball tournaments revealed a tactical intellect paired with athletic prowess. Despite notorious extravagance and rebellious partying that branded him the family’s "black sheep," his commitment to mastering seafaring never wavered. Petrified in humanity’s global fossilization event, Ryusui was later revived by Senku Ishigami for his unmatched nautical skills. He theatrically demanded adoration as a self-declared leader, yet his true drive merged voracious greed with a vision to reconstruct civilization. Introducing currency to the Stone World, he harnessed economic ambition to galvanize progress, sparking friction with Senku over its ethical deployment. A quick study, Ryusui mastered emerging technologies like drones and radar while relying on instinctive "sailor’s sense" to navigate storms and chart courses. Standing tall with a muscular frame, Ryusui’s blond hair and anchor-etched eyebrows underscore his bold presence. Post-revival, he dons a crimson trench coat and captain’s hat crafted by Yuzuriha Ogawa, his original stone markings replaced by war paint symbolizing rebirth. As the Kingdom of Science’s linchpin navigator, Ryusui oversaw the Perseus warship’s hybrid construction, blending ancient craftsmanship with modern engineering. Twice petrified during the Treasure Island crisis, he engineered oxygen tanks to rescue allies and pinpointed fossilized comrades using strategic deduction. His protective instincts surfaced when shielding Suika from petrification, later praising her pivotal role in missions. He mediated internal strife, confronting Hyoga’s betrayal, and battled adversaries like Ibara with tactical ferocity. Brash yet perceptive, Ryusui declares all humans equally "beautiful," celebrating ambition and desire as catalysts for advancement—embodied in his motto, "Wanting something equals justice." Though flamboyant, his loyalty to the Kingdom of Science and partnership with butler Francois, who shares his zeal for societal rebirth, underscore a selfless dedication to global restoration. Holding the record for surviving repeated petrification, Ryusui’s legacy spans founding the Ryusui Foundation to spearhead reconstruction, pioneering economic systems, and charting uncharted seas—cementing his role as both provocateur and visionary in humanity’s rebirth.