TOKYO In Japan, cleanliness is not just a personal issue, but a public one. The day I realized this, I was sitting on the Tokyo subway and a man seated across from me leaned over and pointed at my shin.

Alarmed, I looked down, and there, on my otherwise clean black pants, was a rather innocuous mark. As it happened, I was housesitting for a large dog that week. Was it, quite possibly, a small smear of dried dog slobber?

In New York or Paris or Hong Kong, other cities where I have lived, nobody would have noticed. But in Tokyo, my appearance seemed to be the concern of everybody else in proximity, including at that moment the man across from me on the train. I'm sure he was just doing me a courtesy. Yet, feeling apologetic and as though I had caused offense, I reached down sheepishly and brushed it off.

So it was with slight trepidation that I bundled up my dirtiest clothes and made a trip to a dry cleaner. Striding in, I produced a blue silk top. The dry cleaner spread it on the counter and studied it carefully. He seemed particularly interested in some white streaks under the arms, which he touched gingerly.

"What is this?" he demanded in Japanese.

Even if I didn't speak Japanese, there could be no misunderstanding. I hadn't yet learned enough Japanese to respond, however, so there was nothing I could do but stand there, raise one arm, and mimic the act of rolling on underarm deodorant. He looked at me strangely.

"Sweat, eh?" he asked accusatorily, this time in English. Meekly, I shook my head, raised my arm and tried again.

I considered fleeing, but instead I began to apologize.

"Excuse me," I said.

He stared at me for a moment and then motioned for my next garment. I bowed slightly, repeated my apology, and placed a light gray suit jacket on the counter.

Here, again, was a small spot, this time near the front right pocket. It was just a speck of something - coffee, maybe, or soy sauce - but the dry cleaning man seized on it.

"Stain!" he said, poking his finger at the mark.

Yes, I admitted. I had stained my jacket. "Excuse me," I repeated.

But that wasn't all. The jacket had a belt, and he started to remove it to hand it back to me. It would cost ¥100, or 85 cents, to clean, so it could only be worth cleaning if it were dirty, too.

But only I knew the belt's dark secret. In a moment of carelessness, I had leaned over in a bathroom stall and one end had fallen in the toilet. It was dry now; there was no mark, no stain.

"Excuse me," I said again, urging him to leave my dirty belt on my dirty jacket.

With the sudden realization that I was indeed dirtier than even the dry cleaner imagined, I worked my way into a full-blown apology.

"I'm sorry," I said, lowering my eyes. Yes, I had left marks on my silk shirt; I had splashed something on my jacket, and I wanted my belt cleaned, too. That was why I had come to the dry cleaner's.

And I was deeply, deeply sorry. Apologizing to the dry cleaner for having dirty clothes seemed a bit beyond the course of normal commercial interaction, but wholly necessary.

Seeing that I was contrite and a little embarrassed, the dry cleaner was satisfied with my initiation hazing.

He pinned on the tags, threw the clothes in the bin, and asked me if I had a membership card. Surely I needed a membership. He would be happy to sell me one for ¥200.

I wasn't planning to be in Japan for more than a few months, but it seemed like a bargain. I could tell from his look that he knew I would be back, and not just to pick up my newly cleaned clothes.Purged of my dirt and newly initiated, I had just become a card-carrying adherent to the cleanliness code.

Sheridan Prasso is a Japan Society media fellow in Tokyo and a contributing editor at BusinessWeek magazine.