Mathematical modeling and regionality-based optimal policy to reduce empty houses, Akiya, in Japan

Empty houses, Akiya, are of substantial concern to the ageing society of Japan; the ratio of Akiya is projected to worsen to 30.5% in 2033. Such a high ratio of Akiya will influence the social system and the Japanese economy overall in the near future. Nonetheless, Akiya continues to increase unabated because there are no specific government measures to address the problem. In this study, we develop a simple mathematical model based on Markovian transition whereby we anticipate the future tendency of empty houses based on real data. Using the model, we demonstrate three tax policies and estimate the effectiveness of the policies considering the extent of Akiya and local government financing. We also consider the spatial distribution of Akiya and suggest both a spatially and quantitaviely effective policy that could reduce Akiya. Our study suggests that to solve the Akiya problem, tax policies and spatial policies should be initiated together, and the policies should be conducted strategically based on the regional characteristics of cities such as economic scale and the population age distribution.