Kaseki, Ishigami Village's elderly master craftsman, possesses exceptional skill honed over fifty years. A descendant of Byakuya Ishigami's crew, his youthful passion for invention caused isolation among villagers who disdained his interests. Yet, he designed and built much of the village, including its bridges, and crafted shields like the one later wielded by Kohaku's father. Initially wary of Senku, Kaseki becomes a fiercely loyal Kingdom of Science member after witnessing Senku's science. Forcibly brought to assist with glassblowing, he breaks his bonds upon seeing Senku and Chrome's amateur attempts, taking over the process with inherent understanding. He plays a critical role in crafting essential inventions: gas masks for retrieving antibiotics, Japanese swords for warriors, engines, and vacuum tubes. The petrification's rejuvenating effect grants him surprising physical strength, enabling feats like tearing ropes despite his age. His expertise drives large-scale projects: constructing a water wheel for electricity, collaborating on cellphones while marveling at their communication potential, and building the exploration ship Perseus, which he joins as crew. On Treasure Island, Ibara's forces petrify him and shatter his body. Depetrified and repaired, he assists in creating a drone and later repairs the Perseus. He participates in confronting Why-man, expressing shock at the entity's resemblance to Senku. Kaseki further contributes to space travel endeavors, modifying aircraft and constructing runways. He collaborates with Yuzuriha to build an elaborate globe model based on Senku's plans, demonstrating shared precision. He remains active in Kingdom missions, traversing the Panama Canal and South America. Personality-wise, Kaseki exhibits pride yet humility about his work, often seeking validation, particularly from women. He forms strong bonds with Senku and Chrome, valuing their shared passion for creation across generations, and imparts wisdom while admitting shortcomings. Typically unassuming, project excitement unleashes boundless energy, sometimes bursting his clothes to reveal a muscular physique. He shares a notable dynamic with Gen Asagiri, frequently recruiting him for assistance and leveraging his imposing presence to ensure compliance.