It was only a two-foot-high pickle barrel, a thoughtful gift from relatives in the countryside, but the Sato family had nowhere to put it.

In their typically tiny Japanese house, the kitchen already is crammed to the ceiling, there is no basement and the yard is, as the Japanese say, "the size of a cat's forehead."

So the pickle barrel went outside, in the narrow sliver of a pathway that separates the Satos' house from the one next door. Every time the Satos reached for a scoop of pungent Japanese pickles, the lady next door went bonkers.

"Space has a huge impact on Japanese lifestyle; it even affects your relations with the neighbors," said Eri Sato, 30, whose father hasn't spoken to his longtime neighbor since she demanded in a huff that he put the stinky pickle barrel out with the garbage.

Perhaps nothing defines Japan, the Japanese psyche and a Japanese person's daily life more than space -- or the scarcity of it. From the long commutes needed to reach affordable living space to the adaptability needed to make swimming with nine other people in the same lap lane seem enjoyable, the tight boundaries of this island nation dictate the way the Japanese live.

Crowding has created some of the most familiar and lasting images of Japan. But no single picture captures the intensity and relentlessness of the crush of people. Even hours of driving on a highway from the center of Tokyo doesn't take you out of the sprawl. Osaka is 240 miles and three hours from Tokyo on Japan's super-fast bullet train, and the view of concrete and asphalt out the window rarely changes.

Most of Japan is virtually uninhabited, stretching across mountains, remote islands and rural areas. Almost all of its 126 million people live in huge urban swaths, where space is so tight and expensive that millions of adults like Sato live with their parents because they can't afford places of their own. The average Tokyo dwelling is about 620 square feet.

Sato said the density leads to more than just sweaty crowds. She said it also alters personality and behavior. She said her own routine is affected by being able to hear every time a neighbor flushes a toilet, turns on a washing machine or shouts at his children.

"I am conscious of keeping my voice low, of generally keeping a low profile, even in my own house," she said. "You definitely have a feeling of no privacy."

Japanese daily life is filled with rules and more rules, and many of them exist because of the space shortage. In Tokyo neighborhoods, trash is picked up four times a week, mainly because people have no place to store it. And the trash must be carefully sorted into burnable and non-burnable loads, and put out in government-approved see-through plastic bags so it is easy to spot violations.

Violating the trash rules can often bring the wrath of the dreaded "trash lady," the self-appointed neighborhood cop who keeps an eye on everyone's garbage. Many neighborhoods have one, and it is not unusual for them to report offenders to police, who issue fines and written warnings. Tokyo residents who put a bag of aluminum cans out on "burnable trash only" day can find a trash lady running out of her apartment yelling, "No! No! No!"

The trash lady is more than a busybody; she's the space police. Carelessly tossed garbage, or piles not efficiently sorted, can be a hazard in a city where streets often are barely wide enough for one car to pass. Many streets have no sidewalks and people's front doors open directly into the road, so pedestrians, drivers and residents all depend on clockwork garbage collection.

Sato said others who violate the unwritten space etiquette can suffer from the "silent rule," where bad behavior is met with a silent, judgmental stare. Turn on the washing machine too early? Park your car too close to the neighbor's door? Try to cut in line at the movies? "Things can get very awkward," Sato said.

But the lack of space also has encouraged innovative design. Japanese engineers trying to adapt to their nation's hyper-crowded conditions perfected transistor radios, compact cars, the Walkman, cellular telephones the size of a candy bar and television sets as thin as a piece of toast.

Japanese vending machines have become an extraordinary space-saving alternative to corner stores -- and even the beauty salon. Some vending machines now provide a $12.50 manicure: Drop in the money, select a color or design, and get two fingers at a time painted by an automated brush.

Many sociologists, architects and social critics interviewed recently said there is a close link between such crowded living and the remarkable orderliness, courtesy and group awareness of the Japanese. They say it also influences Japan's scrupulous attention to the tiniest details in design of cars, buildings or products.

"The concentration of space makes the concept of order very important," said Hiroyoshi Ishikawa, a professor of psychology at Seijo University in Tokyo.

Prime Minister Keizo Obuchi regularly mentions his goal of raising Japan's quality of life by trying to increase the size of housing and provide more parks and open space. In general, Obuchi favors construction of taller but fewer buildings, leaving more green space between all the concrete.

Tokyo is a surprisingly low-rise city, in large part because of people's reluctance to live in high buildings in a city so prone to earthquakes. But engineering know-how has made taller buildings safer on shaky ground, and the demand for open space is rising.

The government is trying a subsidized loan scheme to help people buy larger homes. The idea is to make them affordable to middle-class families, and to give construction companies financial incentives to build one large home on a vacant lot, rather than two small ones jammed together.

"Japan today is at the top of the world in clothing and food, but when it comes to housing, we fall behind," Obuchi said in a recent interview. "My greatest hope today is to improve the living environment."

As things stand now, Obuchi said, "even rich people do not have a house they can invite a guest to." Indeed, many large companies own guest houses for entertaining by their top executives, who often don't have a home large enough to accommodate dinner guests.

But for most Japanese, such as computer engineer Junji Ohashi, life in one of the world's richest societies continues to be a curious contradiction: affluence without ease.

Ohashi, his pregnant wife and their two children live the typical upper-middle-class Japanese life in their tiny apartment on the sixth floor of a drab suburban building. Ohashi paid $420,000 eight years ago for the 645-square-foot flat, which is a two-hour commute by train from his office.

It's a two-magazine-subscription apartment: Ohashi used to get three, but with the family's possessions already piled to the ceiling, there was no place to put a third stack. There is one bathroom, no clothes dryer (clothes dry on a line on the tiny balcony), a compact refrigerator, and two kids' bedrooms the size of walk-in closets.

"It's too small," Ohashi said, sitting cross-legged on a floor pillow in the living room, surrounded by bookcases, stacks of videos, a television, a compact disc player and an upright piano.

"But it's not frustrating," he said. "I guess I'm just accustomed to it."

Special correspondent Shigehiko Togo contributed to this story.