Also never been, but from pictures I see of their trains and stuff, seems like a lot of their public transport gets pretty cozy.
Been to Japan many many times. My Western point of comparison is German, Belgian, French cities, as well as America.
Japanese spaces are small and cramped, and people are accustomed to crowding together. So I would not give them any advantage on physical proximity, if anything it may be slightly worse. However, almost everything else about Japan would be better: systematic facemasks, bowing, frequently cleaning everything squeaky clean in public spaces, toilets segregated from bathing spaces. Literally all toilets have water spray functions. They are still taking off/changing shoes at most houses, most traditional restaurants, and change shoes again when going into the bathrooms. Even schools and factories change to indoor shoes immediately before entry. Japan has no PDA and even holding hands is rare to see. They do eat eggs, meat and seafood raw, but never walk around eating or drinking. Smoking is common but not universal anymore. Water fountains do not exist, cheap and common vending machines fill in.
In Europe cities I would say you have all of the crowding and none of the hygiene. They cram into trains and busses just the same except the trains, busses and stations are basically filthy by Japanese standards. Don't even mention the restrooms. They also go around eating in public, shaking hands, kissing everyone they meet, and also smoking. In America we add hugging, add eating food with our hands, add obesity, add walking around constantly with coffee or Big Gulps, and subtract smoking, kissing, and most public transport.
Overall I would say if Japan turns out to be better I would say the 6FT rule is bogus, but just clean everything obsessively and don't touch anyone. So Nikola Tesla was right basically.
