In this study, the author analyzed the cultural fitness of win-win cooperation by focusing on the benefit sharing system, which has recently been spotlighted as a representative method of win-win cooperation between large and small-medium enterprises. The author conducted semi-standardized interviews and structured observations of firms operating benefit sharing systems in Korea, the United States, and Japan. The results revealed that Japanese supply chains, where knowledge-based trust and identification-based trust are evenly formed, utilize a balanced mix of methods including suggestion systems, supplier development, and joint new product development (target costing). American supply chains, where calculus-based trust and knowledge-based trust are formed, primarily utilize suggestion systems and supplier development methods. In contrast, Korean supply chains, where identification-based trust and knowledge-based trust are weak, primarily rely on suggestion systems. The finding of this study that cultural fitness exists in the operation of benefit sharing systems not only fills a research gap regarding the relationship between win-win cooperation and culture, but will also provide useful guidance to firms deliberating the adoption of benefit sharing systems and to policymakers working to promote the diffusion of such systems.