Like many Zen-inspired buildings, Okawara's Tokyo home is a monument to simplicity. The size of a large tool shed, the wood building blends seamlessly with the surrounding park. His door opens to a full view of the Tama River.

Okawara is not your typical architect: He's homeless. But the elegant austerity of his home and thousands of others like it has turned Japan's most destitute into unwitting purveyors of an emerging art form that's catching the eye of international connoisseurs.

The homes — carefully built, meticulously kept and collapsible for quick movement when the police move in — have inspired a rash of art books, and Japanese promoters are discussing them with curators in North America and Europe.

Fans are inspired by the homes' design and functions: elaborate triangular roofs, or intricate networks of metal piping to keep the structure standing. One of the books pointed out a home powered by solar batteries.

Even to the untrained eye, the homes of Japan's homeless are remarkably well-built and cared for. Some are fitted with traditional Japanese tatami mats; others boast extensive gardens with neatly trimmed camellias and bonsai shrubs.

The architects themselves are modest.

"The house wasn't so hard to make, because I kept the structure to a minimum," said Okawara, who wanted only his last name used because of social stigma associated with homelessness in Japan.

He said he had purchased many of the materials at a hardware store — like the spotlessly clean floorboards to his bedroom. "It sometimes gets cold, but I like the view of the river," Okawara said.

But experts see in the homes an artistic creation with deep roots in Japan's austere Zen Buddhist tradition.

"These homes embody simplicity, functionality and are at one with their environment, like the tea house of Rikyu Sen," says architect Kyohei Sakaguchi, referring to a 16th-century tea master who preached frugality through the Japanese art of tea ceremony.

Sakaguchi published a study of homeless architecture, "Zero Yen Houses," in 2004.

"I don't want to idealize the situation homeless people find themselves in," he said. "But in a world where most of us live in mass-produced, concrete boxes, Zero Yen Houses are precious works of art. They deserve to be recognized."

Sakaguchi is trying to achieve just that. He is working to bring an exhibit based on homeless architecture to an art gallery in Vancouver, Canada, later this year, and has discussed similar ideas with galleries in London and the United States.

In his recent booklet, "Asakusa Style," photographer Kanta Sogi wrote that he was overwhelmed the moment he first saw some of the houses.

"Since then, I've seen many more houses, and my feeling of wonder has grown ever stronger," Sogi wrote.

The modish world of museums and art galleries couldn't be further away from the realities of life for Japan's estimated 25,300 homeless, who are largely seen as a shameful blight on the country's orderly, affluent society.

Homelessness was mostly unheard of in affluent Japan until the economic boom of the 1980s ran off the tracks in the early 1990s, prompting a 15-year-long run of corporate restructuring and layoffs that clotted urban parks and river embankments with the destitute.

Street dwellers often are harassed by police, who periodically drive them from riversides and parks. Just recently, a crowd of homeless people clashed with hundreds of police and public employees who knocked down their makeshift homes in the western city of Osaka to make way for springtime flower festivals.

The homeless deal with this plight in ingenious ways. The houses are often collapsible, allowing inhabitants to quickly fold them away on news of police raids, only to rebuild them several hours later in the same place.

"I used to try to keep fit, but I've been a little slack this winter," Okawara said, glancing at a makeshift exercise bench at one corner of his small but neat garden. Orderly rows of cooking utensils lined the shelves of a small lean-to.

Farther down the river, Shoji, 65, says he plans to stay put in his house as long as authorities let him despite being eligible, at age 65, for state-run housing.

"I have a sturdy house and I'm free to do what I like," Shoji said of his hand-erected, cubic home, sitting on 5-foot stilts to prevent flooding.

"That's much better than going to a shelter," he said.