[pjc50]

This list seems like a plausible set of causes: https://edition.cnn.com/2018/03/02/health/hong-kong-world-lo...

Given that this is Marginal Revolution, I wouldn't expect them to accept any of the answers that involve state intervention.

There's another possibility: several of the "oldest person in Japan" were found to have been dead for some time and their relatives were claiming their pensions.

[simonsarris]

Yes just like the "Blue Zone" diet areas were found to be curiously poor parts of countries. It turns out they weren't the places with the most residents over 100, they were the places with the most... poor record keeping and fraud.

https://www.biorxiv.org/content/10.1101/704080v1