The 1960s period witnessed the most important internal migration of Japan's population since the modern period with the definitive shift from a rural to an urban-based society. This unprecedented transformation led the Japanese central government to request visions for the prospective development of the national territory in an open competition. Responding to this call, a wide range of reports were produced and debated between 1967 and 1972, mobilizing a vast network of influential representatives in city making, such as sociologists, economists, urban planners, and architects. This article analyzes these reports on the theme of the conservation of natural and historical heritage. To support a sustainable development that was adjustable to economic and social change, the reports emphasized the aesthetic and environmental value of natural landscapes and traditional lifestyles. The reports also proclaimed the rise of an information society and stressed the growing importance of leisure and tourism activities, nowadays one of the most profitable industries worldwide. Apart from their value as interdisciplinary reflections on problems related to urban expansion with visionary qualities, the reports were also highly relevant because they influenced later policies on urban planning and heritage preservation.