This study presents the case study of the lesson study in a primary social studies classroom in Japan. The result indicates to propose a new method of social studies lesson study. While previous method tended to pay less attention to the context of school and children because of the focus of generalization, this study highlights the reality of diverse children in a classroom settings. Throughout the study, we compared the two items: The structure of the subject, namely, triangle relation of goals, contents, and methods and learner 's learning structure. Comparing the two items, we could see the effect of the process of teaching and learning on the children. It means that we can propose the new method by focusing on the reality of the classroom.