The total population of Japan reached its peak in 2008 and has since experienced population decline. This trend has had a profound effect on many of the country's spheres of activity. The purpose of this article is to comprehensively review the existing literature, mainly published since the peak year, through the perspective of the impact of Japan's depopulation on its population geography and to present future research issues based on the obtained findings. Consequently, three new research issues are presented as the lessons learned from the country. First, since the population decline of a country is a very serious problem, population geographers need to devote much more attention to this issue. Second, new analytical methods suitable for examining depopulation need to be developed carefully but actively. Third, population geographers should proactively state policy implications based on research findings associated with population decline. This is a great opportunity to improve the position of the sub-discipline in the countries whose populations have already started or are about to decline.

中文翻译：

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探索人口减少对一国人口地理的影响：日本的经验教训

日本的总人口在 2008 年达到顶峰，此后经历了人口下降。这一趋势对该国的许多活动领域产生了深远的影响。本文的目的是从日本人口减少对其人口地理学的影响的角度，对主要从高峰年开始发表的现有文献进行全面回顾，并根据所获得的研究结果提出未来的研究问题。因此，提出了三个新的研究问题作为该国的经验教训。首先，由于一个国家的人口减少是一个非常严重的问题，人口地理学家需要更加关注这个问题。其次，需要谨慎而积极地开发适合检查人口减少的新分析方法。第三，人口地理学家应根据与人口下降相关的研究结果，主动说明政策影响。这是提高子学科在人口已经开始或即将下降的国家的地位的绝佳机会。