data japan 2023The 2025 population density in Japan is 338 people per Km2 (875 people per mi2), calculated on a total land area of 364,555 Km2 (140,755 sq. miles). Largest Cities in Japan # City NamePopulation Pyramids: Japan - 2025. Other indicators visualized on maps: (In English only, for now) AIDS estimated deaths (UNAIDS estimates)