No not that kind of mask-- one of the first things that hit you when you arrive is the groups of people walking around with masks on;
They are worn because they don't want to spread sickness-- i.e. if someone is wearing one they likely have a cold. It seems fruitless to me because the masks are those thin dentist like masks and I can't imagine they're doing much to keep the germs at bay.
My brother suspects that it's all show-- the Japanese want to show their bosses how dedicated they are to show up for work while they are sick-- and I have to say that seems likely to me.
It would be a heck of a lot cooler if they wore those Kabuki masks instead.
Now these masks would scare away germs.