Kaseki is the elderly master craftsman of Ishigami Village, wielding over fifty years of experience creating tools and structures. He possesses a short stature, a large white beard, bushy eyebrows that obscure his eyes, and wears a simple monk-like tunic. When passionately immersed in work, he bursts through his clothes, revealing a surprisingly muscular physique that mirrors his intense dedication. Descended from astronauts who survived the global petrification event, Kaseki endured youthful isolation due to village disdain for his crafting obsession. Undeterred, he designed and built critical village infrastructure, including bridges and combat shields like the one awarded to chieftain Kokuyo. His skills remained largely unappreciated until his encounter with Senku and Chrome. Kaseki’s personality blends pride in his artistry with a deep-seated need for validation, especially from women. He exhibits boundless energy when excited by projects but initially grappled with loneliness after decades of solitary work. This changes upon joining the Kingdom of Science, where he forms close bonds with Senku and Chrome, cherished friends. His emotional nature surfaces when moved by scientific achievements or expressions of camaraderie. Technically, Kaseki demonstrates genius-level craftsmanship, rapidly mastering unfamiliar materials like glass on first exposure. He constructs complex inventions—vacuum tubes, engines, and precision weaponry—solely from Senku’s diagrams. His physical strength, honed by labor and enhanced by petrification’s restorative effects, allows feats like rope-snapping during enthusiastic outbursts. Despite limited combat experience, his work ethic proves indispensable. Key development occurs across major arcs: - Early contributions include gas masks for antibiotic retrieval and pivotal encouragement to Ginro about overcoming fear. - During village conflicts, he forges swords for warriors and aids in fire prevention efforts. - In communications projects, he co-creates a waterwheel generator and vacuum devices for telephones, tearfully inspired by recorded music from Senku’s adoptive father. - The "Age of Exploration" sees him awed by Ryusui’s weather prediction and collaborating on shipbuilding. His emotional reaction to the hot air balloon’s maiden flight underscores his belief in human desire driving progress. - On Treasure Island, petrification shatters his body, but revival allows drone construction assistance. Later, he repairs the Perseus ship and participates in global resource gathering for space travel. - Post-global depetrification, Kaseki crafts a massive world map with Yuzuriha, exceeding Senku’s expectations. He later modifies aircraft and constructs runways during the New America City mission. Kaseki evolves from a solitary artisan to a communal figure whose wisdom and technical prowess remain vital to the Kingdom’s scientific advancements.