Various theories have been put forward for Japan’s low per-capita COVID fatalities, despite having the world’s oldest population. One theory, reports CBS News, is that the country’s pandemic resilience is due to the willingness of Japanese citizens to cooperate with antiviral measures.

“Japan’s approach to COVID response has been primarily relying on people's effort,” not on imposing mandates, Research Director Kenji Shibuya told CBS News. “These kinds of voluntary efforts, rather than top-down, draconian measures, did work.”

“Scientists probe Japan’s remarkable COVID success in hunt for new vaccine to protect some of the most vulnerable,” CBS News
https://www.cbsnews.com/news/japan-covid-success-factors-hla-cellular-advantage-new-vaccine-research/

Profile of Research Director Kenji Shibuya
https://www.tkfd.or.jp/en/experts/detail.php?id=653