Japan’s population peaked in 2008; the country has been losing inhabitants since then, with geographical disparities in terms of degree of demographic shrinking and territorial devitalisation. Metropolitan areas like Tokyo are still demographically growing whereas many small and mid-sized cities have been losing their population, but this is under-investigated in literature on shrinking cities and urban dynamics, especially in English. This paper attempts to clarify the types of indicators that correlate with social population change in “non-metropolitan urban Japan”: we have tried to identify potential correlations between social migratory population change (measured by net migration) and some social and economic indicators in small and mid-sized cities (population under 50,000). From 2010 to 2019, we picked 30 municipalities that have regis-tered the biggest demographic gains thanks to social migratory increase (in-migration), and 30 others that have suffered the biggest population losses out of social migratory decrease (out-migration), so as to see if there is any statistical difference between these groups with regards to certain economic or social indicators