Hong Kong (CNN) -- Hidden amid the multi-million dollar high-rise apartments and chic shopping malls of Hong Kong's urban centers are scores of tiny, unseen tenements -- some no bigger than coffins -- that many people call home.

Mak, 72, has lived in his four-walled "coffin home" overlooking the city's Wan Chai neighborhood for the past decade. His entire living space is no bigger than a twin-sized bed, and has just enough room for him to sit up.

"No one wants to live here, but we need to survive," said Mak, who works as a janitor at the nearby Times Square. "It's a step up from being on the streets."

Nicknamed coffin homes for their physical similarities, the 15-square-foot enclosure is just one incarnation of the city's distinctive low-income housing alternatives. Others include the city's cage homes, which resemble livestock coops.

Twenty tenants in Mak's building share a communal bathroom that doubles as a shower. Hallways are clad with slapdash wiring and bad ventilation -- and bedspaces are stacked atop one another like kitchen cupboards.

"There's a stigma about those living in these places. People think that it's because they are lazy, but that couldn't be further from the truth," said Sze Lai San, a social worker based in Hong Kong. "Sometimes their jobs just pay very little despite their long hours and hard work, or they just fall on hard times."

And Mak is no exception. A Hong Kong native, he went bankrupt after a series of unsuccessful ventures in finance and now makes barely enough to cover his rent -- around $150 a month.

He is now among the 1.2 million Hong Kong residents who currently live in poverty, according to a government advisory group.

"I can skip meals, ignore the dirt, bedbugs and stuffiness, but the biggest problem we have here is safety," Mak said. "There have been close calls over the years. We're stacked like sardines, and there are no regulations. We'd all be dead if a fire were to start."

Knee-deep in debt, Mak refused to give his full name, fearing that creditors may learn of his whereabouts.

Despite the conditions, Mak's bedspace is one of many similar facilities licensed by the government. According to a city ordinance, any flat with 12 or more bedspaces for individuals under rental agreements must obtain a special license.

But according to an e-mail from Home Affairs spokesperson Elain Chu, "the Ordinance was not formulated to prohibit or illegalize bedspace apartments" and only mandates that rented apartments meet current fire and safety codes.

The reason being that living conditions are "determined by various factors, such market situation, economic environment, personal financial capacity [or a] personal choice and so on," Chu said.

For Sze, the "coffin home" phenomenon is the result of an urban perfect storm: a combination of skyrocketing real-estate prices and arguably the biggest wealth gap in Asia.

A 2011 survey by Savills -- a real estate company based in the UK -- found that the city's top end properties sell for a confounding $10,550 per square foot.

But even the second-tier properties are around 40% more expensive in Hong Kong than in other global cities like London, New York or Moscow, the report found.

Hong Kong: A property boom you can feel

"Hong Kong has gotten more and more wealthy, but these people have been left behind," she said. "A dweller once said to me, 'I'm not even dead yet but I'm already living in my coffin -- four walls and nails'."

Sze -- who has handled cases similar to Mak's for more than 16 years -- said coffin dwellers pay a larger percentage per square foot for their homes than they would for high-end properties. She said that in the past year, the rent for coffin homes has increased by roughly 20 percent.

"There are some very backward practices that should not be happening in Hong Kong," Sze said. "People in low-income housing need more rights. They shouldn't be living on the edge."

Sze said more than 300,000 people in Hong Kong are currently waiting for public housing. And although the average waiting time is three years, many wait in cramped spaces, like coffin homes, for as many as 10 years.

Living in a cage in Hong Kong

Through Mak's eyes, there are two Hong Kongs: The one seen through his only window, personified by the glitz and glamour the city is famous for. And the one inside, that has allowed less fortunate citizens to fall through the cracks.

"It's not that the H.K. government can't help people like me who are part of the low-income society and need help," he said. "It's that they don't want to help people like us and solve problems like this."