Planning a 'sustainable city' with hinterlands: The case of Yokohama City, Japan and its soft space planning to reach net-zero.

This article examines Yokohama city's cross-municipal collaboration initiative to import renewable energy from surrounding rural municipalities (hinterlands) as part of its urban sustainability strategy. It highlights how this initiative expands the geographical scale of urban sustainability beyond city boundaries through non-statutory "soft space" planning, yet reveals persistent power asymmetries favoring the city over hinterlands in decision-making and benefit distribution. The study finds that while the collaboration acknowledges the hinterlands' role in supplying clean energy, the lack of formal governance structures, limited democratic representation, and political uncertainties challenge the initiative's sustainability and equitable outcomes. The research suggests that addressing these power imbalances and enhancing recognition of hinterlands' contributions may require coordinated efforts involving both local actors and higher tiers of government.