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Handrails run down the middle of the hallway to help prisoners make their way from one end to the other. Adult diapers are neatly stacked in a corner. When an inmate chokes on his rice and coughs, a supervisor rushes over to rub his back.

Welcome to the world of old-age prisons. Japan's population is aging faster than anywhere else, and with that has come an even sharper rise in elderly inmates.

The number of Japanese prisoners aged 60 or older has doubled over the past decade to more than 10,000. That outpaces a 30 percent increase in the general population for that age group. The elderly now represent 16 percent of the nation's inmates.

Though Japan's crime rate remains relatively low, the spike in elderly crime is another sign of the social and economic strains on the once-confident country.

An entire floor has been converted into a pilot geriatric ward at Onomichi Prison, near the city of Hiroshima. The government has also invested $100 million to build larger facilities at three other prisons around the country, and more are planned.

Most of the inmates have been convicted of shoplifting and theft, reflecting the financial pressures and lack of family support facing many older Japanese amid a lengthy economic slump and fraying social cohesion.

About half are repeat offenders, including some who steal to get caught and return to the relative security of prison, where at least shelter — if Spartan — and three meals a day, as well as a twice-weekly bath, are guaranteed.

"I'm already an old man, and the economy is bad out there," a nearly 70-year-old inmate told The Associated Press, which was granted a rare tour of a Japanese prison.

His 3 1/2-year sentence for attempted robbery is up in April, and the prospect of going free fills him with more dread than joy.

"I'm worried that there would be no work for someone like me," he said, adding that he worries his younger brother may shun him. Prison rules forbid using his name and exact age.

Another factor is that longer sentences are being handed out. Also, elderly inmates without family or community ties have virtually no chance of parole, which is only granted for those with a reliable guardian.

"The number of senior inmates has been surging, and there is no sign of decrease," said Koki Maezawa, a Justice Ministry official in charge of prison services. "It's a serious problem that the entire society must tackle so that offenders don't keep coming back to prison once they get out."

The graying of the prison population is not unique to Japan, though it's happening faster here than in other countries, according to the Justice Ministry.

In the United States, the number of inmates age 55 and older in state and federal prisons grew 76 percent between 1999 and 2008, from 43,300 to 76,400, according to the Justice Department. The overall prison population rose by a smaller 18 percent. Those age 60 or older numbered 35,900, or 2.3 percent of the total, a much smaller proportion than in Japan.

The U.S. growth is in part a legacy of laws that mandated harsher sentences or abolished parole, keeping convicts in prison into old age. It has strained government budgets, because of the higher health care costs for elderly inmates.

Several states, including Virginia, Pennsylvania, Louisiana, North Carolina and Ohio, have geriatric prisons or wards. Other countries, including Germany and Britain, have special wings for elderly inmates, and Switzerland is building a similar facility.

Here at Onomichi Prison, the hallways use ramps, not steps, and prisoners are allowed to use walkers if they need them.

The inmates work six hours a day, instead of the eight required of other prisoners, and do lighter tasks such as sorting papers, folding laundry and making beadwork and paper crafts. All prison employees have received training for elderly care, and two are certified assistant nurses.

"We have to provide the kind of attention like ordinary nursing homes," said Yoshihiro Kurahashi, the chief guard at the prison.

Still, the prisoners' lives are strictly regimented, and conditions are hardly comfortable. There is no air conditioning to help endure southwestern Japan's sweltering summers. All inmates must work, even those past retirement age. No talking is allowed at lunch, at work or during bathing; inmates can converse or read or watch TV only during a short period after lunch and at night until lights-out at 9 p.m.

All prisoners wear light-green uniforms and caps. A guard shouts at one who forgets to wear his cap in a quiet workroom, where a red goldfish and a turtle — symbols of wealth and long life — are kept in a fish tank.

Everywhere there are signs that this is not a normal prison.

In one cell, a gray plastic tarp protects the straw "tatami" mat floor from bed-wetting. Mattresses cover the walls of another cell, now empty, to protect a former inmate with dementia who repeatedly banged his head against them. More than half the inmates have some form of dementia.

The prison has a small clinic, but those who need advanced treatment are transferred to facilities with bigger medical wards, such as the one in Hiroshima.

Onomichi's pilot project houses 61 inmates from age 60 to 89. The facilities that have been built at three other prisons will together be able to handle 1,000 elderly inmates when they are fully operational.

Shoplifting is a growing problem across all ages in Japan, but the number of senior offenders has jumped nearly sevenfold over the past decade, according to the Tokyo Metropolitan Police.

In a Tokyo police survey of 1,050 shoplifting suspects last year, the majority of seniors said they were financially troubled or without regular income, single and had no friends. They most often stole food, cosmetics and other small items worth less than 5,000 yen ($60).

"Elderly shoplifting cases have become a major social problem and we have lagged in taking proper steps," said Tokyo police official Fumio Yamashita. "We must seek how to rebuild our social ties."

Japan now has a record 1.3 million families on welfare, of which 44 percent are elderly households.

"Some of the seniors here were convicted of shoplifting after having trouble making ends meet," said Takashi Hayashi, head of the Onomichi Prison. "In a way, they are victims of the bad economy, but that shouldn't be an excuse."

Prison should not be their retirement home, he said. "We want them to regain motivation to live so they can return to society and stand on their own."

The prison has stepped up vocational and welfare programs to help seniors return to society.

"Our main concern is how to keep them from repeating crimes. It would be best if they can support themselves physically and financially. If not, who would take care of them?" said Kurahashi, the prison guard. "Nursing care homes are already full. Who would be willing to accept former convicts?"

With few choices, some regress further, said Taisei Sakuhara, a senior researcher at the Justice Ministry's Research and Training Institute: They attempt more serious crimes, such as arson, to try to get a longer sentence the next time.