I have been arguing for some time that one of the main reasons to wear a mask is to contain the nasal emissions of the mask user, either directly or by sneezing into one's elbow and then brushing it against shop fitments when reaching to get something off a high shelf and passing it on to others that way. I made my mask after sneezing twice a few weeks ago while doing my weekly shop.
I am not sure there is anything particularly Japanese about thinking that way. Surely that is the main reason why medical and surgical staff wear masks - to protect the patient?
In cases where the patient may pose a danger to the staff, obviously staff wear them to protect themselves, but except in exceptional times like now. The majority of masks are worn to protect the patient not vice versa.