Reconstruction of Japanese Population by Birth Year through Vital Statistics Accumulation and Comparison with Census Data: Based on Mortality Structure Estimation for 1944/45 - Methodological Development and Application of Population and Household Projections in an Era of Long-term Population Decline and Large-scale International Migration (Part 2)

This study by Reiko Hayashi reconstructs the Japanese population over approximately 150 years from 1872 to 2023 by accumulating birth and death vital statistics, comparing results with census and other cross-sectional statistics. Since official statistics on age- and sex-specific deaths do not exist for 1944/45 during World War II, estimates were derived from surrounding census data. Results revealed excess deaths of 3.76 million during these two years, with particularly high mortality among men born around 1920 (approximately 25 years old in 1945). The difference between accumulated vital statistics and census data as of 2020 was only 0.3% of the total population, confirming consistency between these institutionally unlinked statistical systems.