Over the last decade, Japan’s population has aged more and more, to the point where more than a quarter of Japanese were 65 years and older in 2022. Population growth has stopped and even reversed, since it’s been in the red for several years now.

It’s getting old

With almost 30 percent of its population being elderly inhabitants, Japan is considered the “oldest” country in the world today. Japan boasts a high life expectancy, in fact, the Japanese tend to live longer than the average human worldwide. The increase of the aging population is accompanied by a decrease of the total population caused by a sinking birth rate. Japan’s fertility rate has been below the replacement rate for many decades now, mostly due to economic uncertainty and thus a decreasing number of marriages.

Are the Japanese invincible?

There is no real mystery surrounding the ripe old age of so many Japanese. Their high average age is very likely due to high healthcare standards, nutrition, and an overall high standard of living – all of which could be adopted by other industrial nations as well. But with high age comes less capacity, and Japan’s future enemy might not be an early death, but rather a struggling social network.

In 2023, people aged 65 years and older in Japan accounted for approximately **** percent of the total Japanese population. Due to a low birth rate and high longevity, people aged 65 years and older were estimated to make up almost ** percent of the population in Japan by 2070.

In 2020, around *** percent of the population in depopulated areas in Japan were aged 85 or older, as opposed to the national average of *** percent. The largest difference between the national average and depopulated areas could be observed among people aged 60 and older.

According to a projection made in 2023, it was forecast that the number of people aged 65 years or older in Japan would increase from about **** million in 2024 to around ** million people by 2033. By contrast, the number of children, as well as the working-age population, was forecast to shrink in the same period.

Historical chart and dataset showing Japan population growth rate by year from 1961 to 2023.

Population density per pixel at 100 metre resolution. WorldPop provides estimates of numbers of people residing in each 100x100m grid cell for every low and middle income country. Through ingegrating cencus, survey, satellite and GIS datasets in a flexible machine-learning framework, high resolution maps of population counts and densities for 2000-2020 are produced, along with accompanying metadata. DATASET: Alpha version 2010 and 2015 estimates of numbers of people per grid square, with national totals adjusted to match UN population division estimates (http://esa.un.org/wpp/) and remaining unadjusted. REGION: Africa SPATIAL RESOLUTION: 0.000833333 decimal degrees (approx 100m at the equator) PROJECTION: Geographic, WGS84 UNITS: Estimated persons per grid square MAPPING APPROACH: Land cover based, as described in: Linard, C., Gilbert, M., Snow, R.W., Noor, A.M. and Tatem, A.J., 2012, Population distribution, settlement patterns and accessibility across Africa in 2010, PLoS ONE, 7(2): e31743. FORMAT: Geotiff (zipped using 7-zip (open access tool): www.7-zip.org) FILENAMES: Example - AGO10adjv4.tif = Angola (AGO) population count map for 2010 (10) adjusted to match UN national estimates (adj), version 4 (v4). Population maps are updated to new versions when improved census or other input data become available.

The world's most accurate population datasets. Seven maps/datasets for the distribution of various populations in Japan: (1) Overall population density (2) Women (3) Men (4) Children (ages 0-5) (5) Youth (ages 15-24) (6) Elderly (ages 60+) (7) Women of reproductive age (ages 15-49).

Text A, Representation theorem for a right eigenvector of an irreducible non-negative matrix. Text B, Theorem for infinite series expansion of characteristic equation. Text C, Original definition of type-reproduction number. Text D, Extension theorem of type-reproduction number. (ZIP)

Vicia sepium (bush vetch) is a perennial legume widely distributed throughout the Eurasian continent. However, its distribution in Japan is limited to Mt. Ibuki and small parts of central and southern Hokkaido. Therefore, each Japanese V. sepium lineage has been considered to have been introduced separately from Europe. Here, we examined whether the species was introduced or not on the basis of cpDNA sequences and genome-wide SNPs from Japanese and overseas samples. Both the cpDNA haplotype network and the nuclear DNA phylogenetic tree showed that Japanese V. sepium is monophyletic. Furthermore, although the nuclear DNA phylogenetic tree also showed that each lineage is clearly monophyletic, genetic admixture of the genetic cluster dominated in the Hokkaido lineage was also detected in the Mt. Ibuki lineage. Population divergence analysis showed that the two lineages diverged during the last glacial period. The Mt. Ibuki lineage showed a sudden population decline 300–400 years ago, indicating that some anthropogenic activity might be involved, while the Hokkaido lineage showed a gradual population decline from 5,000 years ago. Consequently, these two lineages show low current genetic diversity compared with overseas lineages. These results show that the Japanese V. sepium is not introduced but is native. Methods Six SNP data sets were generated for different data analyses shown in Table 2 in the main text.

In Japan, ** percent of the population was 65 years or older in 2025, underlining the aging population of the country. Among the G7, Japan and Italy had a higher share of people aged 65 years. The United States had the highest share of children and youth between zero and 19 years at nearly ** percent.

Japan is one of the highly urbanized and severely aging society. In an aging society, chronic disease and disability are prevalent, and the population is sensitive to environmental issues and climate change. To detect the impacts of population changes, formulate the population and public health policies, and assist environmental applications, the high-resolution and accurate gridded population dataset is strongly desired. To provide basic data for these studies, we create an open access annual dataset containing the total, male, and female population counts in each grid at a 500-m resolution from 2001 to 2020. The yearly population dataset is based on the 4th-level mesh data from the Statistics Bureau of Japan to make it easy to use. The dataset is provided here alongside the descriptions of the data and methods used in the fitting, cross-validation, and prediction processes.

The total population data are stored in 20 attributes, named the “X0000” style. The “0000” of “X0000” represents the four-digit year. For example, the attribute “X2001” reports the total 2001 population in the mesh. The dataset also preserves the direct output from the random forest and the logarithms of the total population. The attributes of the logarithms of the total population in each year are named in “X0000_log” style. The “0000” of “X0000_log” also stands for the four-digit year. The attributes of the female population, the logarithm of the female population, the male population, and the logarithm of the male population are written as “X0000_fema”, “X0000_fe_l”, “X0000_male”, and “X0000_ma_l”, respectively.

The accuracy of the models constructed to predict the total, male, and female populations are 92.09%, 91.92%, and 92.16%, respectively.

Abstract Understanding how population structure and demography are determined is a central theme in marine biogeography. While historical events, such as past climate change, are important determinants, the mechanisms by which they act are not well understood in many marine species. In this study, the population structure of the Japanese, marine intertidal gastropod Lunella correensis was investigated to determine whether it has been affected by past environmental changes. A genome-wide SNP analysis, L. correensis showed a genetic gradient along the coast and a weak genetic differentiation between sites in the Sea of Japan and the Pacific Ocean. Demographic inference suggests that the effective population size expanded and shrunk in response to periods of rapid warming and cooling due to past climate change. Further, ecological niche modelling suggests that the population size of L. correensis increased by advancing into the Sea of Japan during rapid warming after the Last Glacial Maximum. Notably, our analyses suggest that recent human activities may have influenced the effective population size of this species. Specifically, the period of reduction in the population size coincides with environmental changes and habitat loss associated with development along the Japanese coastal area. Thus, these results emphasize that the genetic structure and demography of marine species have been influenced by past environmental change around the Japanese Archipelago.

The Japanese Archipelago consists of a series of isolated yet interconnected islands off the Eurasian continent. The linear topography of the archipelago presents a unique biogeographic context for the dispersal of organisms from the continent. In this study, mitochondrial DNA (mtDNA) and single-nucleotide polymorphism (SNP) variation were employed to elucidate the dispersal history of the Japanese clouded butterfly (Parnassius glacialis) across the Japanese Archipelago, including the northern island (Hokkaido), the main island (Honshu), and Shikoku Island. Network analysis of 1192 bp of mtDNA (cytochrome oxidase I and II) regions revealed 49 haplotypes and three distinct haplotype groups, which correspond geographically to Eastern Japan, Western Japan, and Chugoku–Shikoku. The Chugoku–Shikoku group is the most ancient lineage. Divergence time estimates using whole-genome sequencing of mtDNA suggest that the Japanese lineage diverged from the continental P. glacialis approximately 3.08 ..., SNPs were detected from the extracted DNA using the genotyping by random amplicon sequencing, direct (GRAS-Di) method designed by Enoki and Takeuchi (2018) and described by Hosoya et al. (2019); this method offers simple library construction and the capacity to detect many SNPs. Briefly, libraries were constructed through two sequential PCR steps, similar to multiplexed inter-simple sequence repeat genotyping by sequencing (Suyama and Matsuki 2015). The first PCR primers consisted of 10 bases of Illumina Nextera adaptor 3-end sequences plus 3-base random oligomers (13 bases). The final PCR product was purified using columns or magnetic beads without size selection and then employed for sequencing on an Illumina platform (Illumina, San Diego, CA, USA). Cyclized DNA was prepared using the produced library and the MGIEasy universal library conversion kit (App-A, MGI Tech) according to the manufacturer’s instructions. DNBs were prepared using the DNBSEQ DNB Rapid Make reagent kit (MGI Tech)..., , # Dual expansion routes likely underlie the present-day population structure in a Parnassius butterfly across the Japanese Archipelago

https://doi.org/10.5061/dryad.69p8cz9d3

Description of the data and file structure

Each sample’s raw fastq sequence data for SNP and haplotype of mtDNA

Files and variables

File: Supporting_Material_PG.xls

Description: Each sample’s raw fastq sequence data and haplotype

Variables

• Sheet 1: an overview of each sheet.
• Sheet 2: raw sequence data for each  SNP detected with the Grass-Di method.
• Sheet 3: haplotype number for each collected individual (collected year, individual code, collection site, Prefecture, Prefecture number, haplotype number)

This bar chart displays population (people) by ISO 3 country code using the aggregation sum in Japan. The data is filtered where the date is 2021. The data is about countries per year.

Urban population (% of total population) in Japan was reported at 92.13 % in 2024, according to the World Bank collection of development indicators, compiled from officially recognized sources. Japan - Urban population (% of total) - actual values, historical data, forecasts and projections were sourced from the World Bank on August of 2025.

This bar chart displays male population (people) by countries yearly using the aggregation sum in Japan. The data is about countries per year.

Longitudinal data set of a nationally representative sample of the population aged 65 and over in Japan, comparable to that collected in the US and other countries. The first two waves of data are now available to the international research community. The sample is refreshed with younger members at each wave so it remains representative of the population at each wave. The study was designed primarily to investigate health status of the Japanese elderly and changes in health status over time. An additional aim is to investigate the impact of long-term care insurance system on the use of services by the Japanese elderly and to investigate the relationship between co-residence and the use of long term care. While the focus of the survey is health and health service utilization, other topics relevant to the aging experience are included such as intergenerational exchange, living arrangements, caregiving, and labor force participation. The initial questionnaire was designed to be comparable to the (US) Longitudinal Study of Aging II (LSOAII), and to the Asset and Health Dynamics Among the Oldest Old (AHEAD, a pre-1924 birth cohort) sample of the Health and Retirement Study (HRS), which has now been merged with the HRS. The sample was selected using a multistage stratified sampling method to generate 340 primary sampling units (PSUs). The sample of individuals was selected for the most part by using the National Residents Registry System, considered to be universal and accurate because it is a legal requirement to report any move to local authorities within two weeks. From each of the 340 PSUs, 6-11 persons aged 65-74 were selected and 8-12 persons aged 75+ were sampled. The population 75+ was oversampled by a factor of 2. Weights have been developed for respondents to the first wave of the survey to reflect sampling probabilities. Weights for the second wave are under development. With these weights, the sample should be representative of the 65+ Japanese population. In fall 1999, 4,997 respondents aged 65+ were interviewed, 74.6 percent of the initial target. Twelve percent of responses were provided by proxies, because of physical or mental health problems. The second wave of data was collected in November 2001. The third wave was collected in November 2003. Questionnaire topics include family structure, and living arrangements; subjects'''' parents/spouse''''s parents/children; socioeconomic status; intergenerational exchange; health behaviors, chronic conditions, physical functioning; activities of daily living and instrumental activities of daily living; functioning in the community; mental health depression measures; vision and hearing; dental health; health care and other service utilization. A CD is available which include the codebook and data files for the first and second waves of the national sample. The third wave of data will be released at a later date. * Dates of Study: 1999-2003 * Study Features: Longitudinal, International * Sample Size: ** 4,997 Nov/Dec 1999 Wave 1 ** 3,992 Nov 2001 Wave 2 ** Nov 2003 Wave 3 Link: * ICPSR: http://www.icpsr.umich.edu/icpsrweb/ICPSR/studies/00156

This bar chart displays rural population (people) by date using the aggregation sum in Japan. The data is about countries per year.

This bar chart displays female population (people) by date using the aggregation sum in Japan. The data is about countries per year.

Constrained estimates, total number of people per grid-cell. The dataset is available to download in Geotiff format at a resolution of 3 arc (approximately 100m at the equator). The projection is Geographic Coordinate System, WGS84. The units are number of people per pixel. The mapping approach is Random Forest-based dasymetric redistribution.

More information can be found in the Release Statement

The difference between constrained and unconstrained is explained on this page: https://www.worldpop.org/methods/top_down_constrained_vs_unconstrained