Pesky aspects of traveling abroad - very dependent on little pieces of paper

I believe that foreigners in Japan are supposed to carry their passport/Visa with them at all times. I generally carry a purse with me at all times, but for my passport I'd prefer something safer - anyone have tips/suggestions? I used an around the neck money pouch while visiting Italy before, but it was incredibly uncomfortable...

Edit: Nevermind! Smaller alien registration card thing, not passport. That be good news.