Kinro is a resident of Ishigami Village, a community of humans who are descendants of astronauts that survived a worldwide petrification event thousands of years prior. As his name, which translates to golden wolf, suggests, he is the older brother of Ginro, the silver wolf. The two brothers serve as the primary gatekeepers of their village, responsible for guarding its entrance and enforcing its laws. Kinro is eighteen years old at the time of his introduction.

Kinro's most defining characteristic is his stern, serious, and unyielding personality. He takes his duty as a guard with absolute dedication, adhering strictly to rules and protocol without compromise. This rigid sense of duty initially makes him hostile to outsiders, including the protagonist Senku Ishigami, whom he views as a dangerous sorcerer. Unlike his cowardly, greedy, and easily distracted younger brother Ginro, Kinro is disciplined, hardworking, and believes that a man should make no excuses for his failures. This deep sense of personal honor and pride is a double-edged sword; while it makes him a reliable guardian, it also leads him to hide his weaknesses. Kinro suffers from severe myopia, referred to in the village as blurry eye sickness, but he refuses to disclose this vulnerability to anyone, fearing it will make him appear unfit for his post.

Despite his initial distrust of Senku and his science-based sorcery, Kinro undergoes significant development. He is first swayed when Senku uses a chemical process to gild the head of his spear with gold, a gift that visibly pleases him even as he tries to maintain his gruff exterior. More profoundly, he is moved by Senku's genuine efforts to save the village chief's daughter, Ruri. Recognizing Senku's noble resolve, Kinro puts aside his reservations and offers his considerable strength to help. He becomes a loyal and trusted member of the Science Kingdom, even vouching for Senku's character to the village elders. This transformation shows his ability to see past his prejudices and acknowledge the value of new ideas, including science. He later even learns to read and write, understanding the importance of these new tools for communication.

Kinro's primary role in the story is as a front-line combatant and defender. He is one of the physically strongest and most skilled spear-wielders in Ishigami Village, with raw power that rivals the village's strongest fighter, Magma. His abilities are severely hampered by his hidden nearsightedness, however, which prevents him from accurately judging distances in combat. This weakness is exposed during the village tournament to decide the next chief, where the young girl Suika lends him her melon-rind helmet, which functions as a corrective lens. With his vision temporarily fixed, Kinro's true combat prowess is revealed as he easily overpowers Magma, demonstrating that his strength had long surpassed his rival. After this event, Senku creates a custom pair of glasses for him, permanently removing his disability and allowing him to fight at full capacity. His key relationships include his exasperated but caring dynamic with his brother Ginro, his respectful rivalry with Kohaku, and his steadfast loyalty to Senku as his chief.

Kinro is present during the Science Kingdom's voyage to North America aboard the Perseus. On this journey, he continues to serve as a reliable member of the crew, using his strength to support the team's objectives. His journey from a rigid, traditionalist guard to an open-minded and vital member of the scientific team exemplifies his growth, proving that even the most stubborn individuals can adapt and thrive in the face of a new world.