What is one of the causes crowded population conditions in Japan?

One of the primary causes of crowded population conditions in Japan is the country's geography. Approximately 70% of Japan's land area is mountainous, leaving limited space for human habitation and economic activities. This natural constraint forces a significant portion of the population to concentrate in the remaining 30% of habitable land, which primarily comprises coastal plains and river basins. This population density puts enormous pressure on available resources, leading to crowded living conditions, particularly in urban areas such as Tokyo, Osaka, and Nagoya.