This article explores the place of Cycas revoluta in Japanese culture, with a specific focus on the Ryukyu archipelago. Although never domesticated, worldwide evidence points to the sustained alimentary, ethnoecological, and symbolic significance of this ancient order of plants since at least the Pleistocene-Holocene transition. Their millennial use in the Ryukyu Islands is a key example of this pattern. Despite this fact, the role of cycads in Ryukyuan and wider Japanese and East Asian cultural systems remains understudied; the broader features of this intriguing aspect of regional culture are virtually unknown outside Japan. This article reviews the social and environmental roles of cycads in ancient and modern Ryukyuan and Japanese cultures, with particular emphasis on their position in indigenous agroecological systems and their incorporation in the sacred landscapes of Buddhist and Shintō religious complexes. In doing so, this article highlights a unique biocultural patrimony and set of ancestral traditions that are in danger of being lost, as cycad habitats succumb to development and as the symbolic significance of cycad use fades from social memory. It concludes with a discussion of how the study of cycads may contribute to contemporary interdisciplinary research and wider heritage discourse to enhance the preservation of the practices, histories, and values related to Japanese cycad culture.