Kaseki, an elderly master craftsman of Ishigami Village, wields unparalleled skill in forging tools and inventions, honed through decades of dedication. As a descendant of Byakuya Ishigami’s crew, he weathered village scorn in his youth yet persisted in crafting, eventually designing vital infrastructure like bridges and shields. His expertise anchors the Kingdom of Science, where he collaborates on projects spanning delicate glass vessels, life-saving gas masks, razor-sharp Japanese swords, and intricate communication devices. Initially wary of Senku and Chrome’s abrasive approach, he soon embraces their scientific vision, seizing control of glass-blowing with instinctive mastery. His intuitive grasp of novel materials—whether shaping molten glass or forging precise vacuum tubes—earns renown, even eclipsing Senku’s technical knowledge. In conflicts against Hyoga and the Tsukasa Empire, Kaseki’s craftsmanship proves decisive, crafting weapons and fortifications. He engineers the Perseus ship, devises a water-powered generator, and constructs a soaring hot air balloon, melding ancestral techniques with cutting-edge innovation. Driven by pride in his work and a playful thirst for admiration—especially from women—Kaseki oscillates between fiery enthusiasm, his aged frame bursting with muscular energy mid-creation, and wistful vulnerability. His bond with Senku and Chrome blossoms into camaraderie, easing years of solitary toil. Petrified and shattered during the Treasure Island crisis, he revives undeterred, repairing ships and assembling drones. Repeated petrification fails to dull his zeal; he tackles aircraft modifications and global infrastructure for space travel with undimmed vigor. Kaseki’s journey mirrors humanity’s resurgence—a once-mocked artisan now pivotal to civilization’s rebirth. He weeps at the beauty of inventions like the hot air balloon, embodying the triumph of perseverance. His legacy, etched in every crafted marvel, celebrates collaboration’s power to transform isolation into shared purpose.