Kohaku is a young woman from Ishigami Village and a descendant of modern humans who survived the global petrification event through generations of oral tradition. She is the younger sister of Ruri and the daughter of Kokuyo, and she serves as one of the central protagonists in the story. Kohaku is widely recognized as the strongest warrior of Ishigami Village, possessing exceptional physical capabilities that include remarkable speed, agility, strength, and endurance. Her combat skills are highly refined, allowing her to fight effectively in hand-to-hand situations and navigate treacherous terrain with ease. She is also an expert scout and tracker, able to locate resources and detect threats using her keen senses, particularly her sharp eyesight. Her knowledge of the natural world, including the properties of plants and medicinal herbs, makes her a valuable contributor to both survival and scientific endeavors. Kohaku is characterized by a fierce and caring personality that combines bravery with a strong sense of justice. She communicates in a straightforward manner and is known for her expressive and often determined demeanor. Her fierce loyalty is one of her defining traits, and she is deeply protective of her sister Ruri, whose illness serves as a primary motivation for Kohaku to ally with Senku and support his mission to rebuild civilization. She is also devoted to the people of her village and later extends that devotion to the Kingdom of Science. Despite her tomboyish nature and reputation as a formidable fighter, which leads others such as Chrome to tease her with the nickname Gorilla, she retains a softer side and shows genuine care for her comrades, particularly the younger members of the group. She is open to the idea of romance and has expressed no objection to the notion of being betrothed to Senku, though he does not share that interest. Her role in the story is that of a physical powerhouse who complements Senku’s scientific genius. She is the first villager Senku encounters after he awakens in the stone world, and she quickly becomes one of his most trusted allies. Within the Kingdom of Science, she serves as a core member of the Power Team, providing the brute strength and practical skills necessary to gather materials, construct infrastructure, and defend the group from hostile forces. Her abilities make many of Senku’s ambitious projects possible. Over the course of the series, Kohaku undergoes significant development. She initially approaches Senku with skepticism, viewing his scientific methods with suspicion. However, as she witnesses the tangible results of his knowledge and sees his genuine desire to help her sister, she grows to trust him completely. Her perspective broadens through her interactions with Senku and other members of the Kingdom of Science, and she gradually develops an appreciation for science and teamwork. Her intellectual growth is evident as she actively learns from Senku and becomes more engaged with scientific concepts. Her relationships are central to her character. The bond with her sister Ruri is the emotional foundation of many of her choices, driving her to take risks and push beyond her limits. Her dynamic with Senku is built on mutual respect; he relies on her strength and instinct, while she admires his brilliance and dedication. With Chrome, she shares a playful rivalry that highlights the interplay between physical prowess and intellectual curiosity, and their complementary skills make them an effective team. She also builds strong connections with other members of the Kingdom of Science, including Suika, whom she looks after with particular care, and Gen, whose strategic mind she learns to appreciate. Throughout the story, Kohaku proves herself to be an indispensable figure, blending raw strength with growing wisdom and unwavering devotion to those she protects.