Resident registration

On Monday, a national "resident registration" system launches. Japan's citizens will be assigned an 11 digit number associated with their name, date of birth and other vital statistics, similar to the US's Social Security Number.

But not every citizen will be enumerated. Two communities in Tokyo, Suginami and Kokubunji, and several other towns around the country, will not participate until better personal privacy legislation is enacted; Yokohama's mayor is making this national registration voluntary for his constituents. This is a hot issue; PM Koizumi received threatening protest letters full of shotgun ammunition.

I don't know the mechanics of the registration process; I wonder if individual citizens will refrain from signing up? All foreign residents are required to carry an alien registration card, so I'm already a number in a Japanese database somewhere. If I had a choice, I wouldn't sign up.