Please let me talk my oinion about Japan a little bit.
Sadly all over the world are suffering from serious virus and no exception in Japan.
But a unique situation of Japan was different from the world.
In Spring normally Hay Fever season is coming up and quite many Japanese people are suffering from serious cedar pollen allergy and they buy many masks in advance for fighting with the pollen. So a large number of people wear masks in spring from the beginning even if the virus have not been expanded.
It might prevent from virus expansion in Japan...