This year he sold it for $75,000, losing a fortune but saying: "You have to move on with your life."
In the four years since President Barack Obama was first elected, thousands of homeowners have faced a similar nightmare in the Nevada gambling city, which has the dubious honor of being America's foreclosure capital.
As November 6 looms, and Obama battles to stay in the White House, there are faint signs of a turnaround, with home prices starting to rise, and the jobless rate down to 12.3 percent in August from 14.3 percent a year earlier.
But it will be a long road to recovery -- a fact Obama is all too aware of, as he tries to convince Americans to give him four more years, to revive the country's shattered economy.
Nagasako, a 43-year-old bachelor, prided himself on being able to pay his mortgage -- but after the 2008 crash, as house prices went through the floor, he realized he was fighting a losing battle.
"Everybody was buying at that time," he told AFP. "I did everything right, I made my payments and everything and then I realized: why am I putting money in something that's worth a lot less?"
So, having joined the massed ranks of the "underwater" homeowners in Vegas -- whose property was worth less than they owed -- he decided to "short sell" it back to the bank, which took possession in return for writing off his debt.
"The last thing I wanted to do was getting out of that house. But you have to move on with your life," he said. "That house was like a big elephant that you keep staring at, and you know you can't overcome it."
At the end of September, 22 percent of properties on the market in Las Vegas were "short sales." Another 7.5 percent were foreclosures, and the remaining 70.5 percent were traditional sales.
But in a sign of possible light at the end of the tunnel -- albeit a dim one -- home prices have crept up for the last six months. And unemployment dropped to 12.3 percent in August, from 14.3 percent a year ago.
"We are definitely going through a transition, (but) it is going to take some time before we start to see pricing really, truly firm up," said broker and property manager Matthew Kalb.
Borrowing is no easier, but the banks have certainly become less aggressive in foreclosing on underwater homeowners, in particular since federal authorities rapped their knuckles -- and made them pay $25 billion -- over illegal or overhasty foreclosures.
"We still have somewhere in the neighborhood of about 58,000 properties in some sort of default," said Kolleen Kelley, head of the Greater Las Vegas Association of Realtors (GLVAR).
But she said: "The market has been steadily increasing. We have had at least six months' straight increase in sale prices," adding: "We're going in the right direction. We're around the year 2000 era of pricing."
Candice Kelley, executive director of the Nevada Hardest Hit Fund, told AFP: "I can't really say with certainty whether we are or are not on the road to recovery.
"I can tell you that foreclosure continues to remain a reality for many homeowners in Nevada, and that there are many more individuals who are fighting to stay in their homes."
But she added: "We continue to see a steady and even increasing stream of homeowners that are taking advantage of our programs so they can avoid foreclosure.
"There are many homeowners that have been hit hard, but there are more and more foreclosure mitigation options surfacing. I am quite optimistic about the many options that are now available to homeowners to address these needs."
Obama -- due to campaign in Las Vegas on Sunday -- has stepped up pressure on Republicans in Congress to back his plans to help borrowers, notably by renegotiating their loans.
Ryan King, boss of realtors Ryan King Group, said: "The only true solution to the problem is massive principal reductions," giving the example of a homeowner owing $350,000 on a property now only worth $200,000.
"Instead of foreclosing an individual and selling the house to somebody else for $200,000, let that homeowner, who can probably afford that home if the loan is readjusted," keep his home, he said.
"Then you have a homeowner living in a property, making payments on it. Banks got bailed out, people never got bailed out. It would be good for the greater good, and I'd be happy about that."
Another silver lining on the Las Vegas property cloud: while house prices have revived -- up 15 percent in the year to August, according to Kolleen Kelley -- for buyers prices still remain at historically bargain levels.
Jay Nagasako is among those benefiting: having sold his under-water home back to the bank, he now lives in a new house a stone's throw away, but "much bigger," which his parents have just bought.
The price? A steal, at $135,000.
