Can the Relationship Population Contribute to Sustainable Rural Development? A Comparative Study of Out-Migrated Family Support in Depopulated Areas of Japan

This comparative study examines how geographic isolation and out-migrant motivations shape support systems in two aging, depopulated rural areas of Japan: Shimogo Town and Nanmoku Village. Challenging the prevailing policies’ focus on internal migration as the primary solution for regional revitalization, we highlight the “relationship population”—a specific group of out-migrated family members who maintain ties to their hometowns—and their diverse contributions to rural sustainability. We employed a mixed-methods approach, including quantitative analyses of aging-oriented household survey questionnaires (using multiple correspondence analysis, multinomial logistic regression, k-means, and two-step cluster analysis) and qualitative analyses of interviews with local government officials and residents (case studies in Nanmoku). Our analysis reveals contrasting support patterns: Shimogo exhibits a localized system driven by resident needs, while Nanmoku employs a strategic approach balancing practical support and community engagement. These findings underscore the limitations of one-size-fits-all migration policies and indicate the need for strategies tailored to the local characteristics of each community. By recognizing the diverse motivations behind hometown visits and the contributions to both residents and communities from the “relationship population”, this research advocates shifting the focus from promoting migration to the interplay of family ties, local support systems, and the agency of residents and out-migrated families. This perspective offers actionable insights for policymakers, local leaders, and researchers working on rural revitalization.