In Tokyo, we live in fear of getting caught putting out gomi, or garbage, at the wrong place, at the wrong time. And the scariest thing about gomi is the ladies--usually older and very proper--who police the rules.

Officially, these are simple: you must separate burnable gomi (household paper, kitchen garbage) from unburnable (plastics) and recyclables (glass, cans, newspaper, boxes). Each must be set out on specified days of the week at a designated spot, where city garbage trucks can collect it. Sound easy? I used to think so too.

One morning a few years ago, the piercing ring of the doorbell jolted my husband and me out of our futon. There was our neighbor, at 6:57 a.m. Forget "Good morning" or an apology for waking us. She immediately began screaming about the trash we'd placed outside the night before. We'd just moved in and hadn't even had a chance to say hello. Yet there she was, berating us for using her spot. We'd also put the waste bags too close to her house, some touching her fence! "Around here," she added, residents put the bags in a big plastic trash can instead of just placing them outside, as we'd always done in our former neighborhood.

That's how I learned that each block or apartment complex has its own laws on gomi. And in our area, this lady was the rule book. We called her the "garbage Nazi," and after that we lived under her thrall. She returned only once, delivering another fusillade for some infraction of the rules. But I would see her from our windows, eying our garbage. "She's checking on us again!" I would whisper to my husband. "What do you care?" he would whisper back. "And why are we whispering?"

It's easy to make fun of such paranoia. But some of us recycle out of fright, not concern for the environment. Take a friend of mine, who one evening came home to find a bag of garbage on her doorstep. "Don't ever mix burnables and unburnables," read the note attached to it, written by her landlord, who had obviously been going through the tenants' trash. She's still quaking. Then there's the Japanese businessman and his wife who went to Singapore and left their three children home in Tokyo. They're worried sick. Will the kids handle the garbage correctly?

Most rules are actually not unreasonable. A plastic container keeps crows from ransacking garbage bags for food, a big problem in Tokyo. Still, some people ignore the rules when they think nobody is watching, and so residents watch each other. Some communities require names on their garbage bags. The latest innovation, I hear, is surveillance cameras that monitor gomi-pickup stations. The goal isn't to expose the offenders but to scare them into honoring the rules. These tactics work because we Japanese hate to stick out.

I never asked my neighbor why she felt entitled to set the rules, or why she had to come banging on the door that early in the morning. I was afraid of being seen as the community troublemaker. We've since moved to another town, where we've yet to meet the local garbage police. I haven't stopped fretting, though. The moment I wake up every morning, I still ask myself: "What is it today, burnable or unburnable?"

The other day, on my way to the train station, I saw a young couple disposing a heap of waste bags at a collection site. Though I had no obvious reason to suspect any wrongdoing, something prompted me to watch. They saw me, with a look on their faces I could describe only as pure horror. Then I realized what had happened. I was turning into a gomi Nazi myself.