The National Institute of Population and Social Security Research released Regional Population Projections for Japan: 2015-2045 (2018) in March 2018. The objective was to project future population by prefecture and municipality. This new round of projections took the results of The Population Census of Japan 2015 (Statistics Bureau, Ministry of Internal Affairs and Communications) as the base population, and it projected the future populations by five-year age group and sex for each five-year period between 2020 and 2045. Until the 2005 round of the regional projection, we first projected prefectural populationand then conducted another projection for municipal population (link to Japanese page). In this new round, we implemented the methodology used in the 2010 round: we first projected populations by municipality and then obtained prefectural population by aggregation of the respective municipalities, except Fukushima Prefecture. Note, because we conducted this projection using the 2015 Census of Population for the base population, the future populations should be regarded as of the date (October 1) for the census.

The geographical units that the projection covered included 1,798 municipalities (23 Tokyo special wards, 128 wards in 12 major cities*, 766 cities, 713 towns, and 168 villages), in accordance with the official boundaries as of March 1, 2018, and one prefecture (Fukushima). The sum of the population in geographical units reported here by age and sex is consistent with the medium-variant fertility and medium-variant mortality projection results of the national projections (published in 2017).