Here are some practical flu masks that are being sold in Japan.
For ladies, non-stick lipstick flu mask:
Flu masks that helps keep your makeup intact:
Flu masks with nose cushion and wet filter that won't fog up your glasses:
Flu masks with a filter that helps soothe your throat:
I read that it is common for Japanese to wear masks when they have a cold. It is a form of politeness towards others because the majority take the public transport to commute from home to workplace.
It's funny to know that Japanese women use the masks for other reasons as well... sometimes they don't have time to put on their makeup in the morning, so they just draw their eyebrow and put on a mask. Later when they arrive at work, they add their foundation, and apply eyeliner, eyeshadow, blush, and lipstick ^^