It is essential to know that there are various cultures in the world and necessary to understand and respect them to live together, also known as “共生 Kyosei.” Japan is assumed to be a homogeneous society, but there are indigenous people who have consciousness detached from Japan. In recent years, the number of foreign newcomers has also been increasing. Under these circumstances, the importance of mutual understanding of different cultures and languages has been made apparent in the field of education, and understanding the diversity of culture in education is being promoted. In this study, three educational practices targeting schoolteachers and adults in the Japanese community to promote international understanding and multicultural education will be presented and examined. The “共生 Kyosei” practices have been found to help teachers design their multicultural education as well as to help students to understand the cultural diversity and help them to realize how they live together with people who have different social backgrounds.