SEOUL, South Korea — The sunlight peeks into Kim Ssang-seok’s home for just half an hour a day. When he opens his only window and looks up, he sees the wheels of passing cars. Mr. Kim dries his clothes and shoes in the sunless inside because of thieves outside. He wages a constant battle against cockroaches and the sewer smell emanating from the low-ceilinged, musty space that is his toilet and laundry room.
This 320-square-foot abode, built partially underground, has been Mr. Kim’s home for 20 years. His late mother smiles from a portrait on the wall.
“You end up in places like this when you have nowhere else to go,” said Mr. Kim, 63, a taxi driver.
But Mr. Kim, a widower, said he was still “grateful that I have a roof over my head and a warm floor to rest on.” He fears the city will clear out his neighborhood in a few years to make room for more of the apartment towers that increasingly dominate Seoul’s skylines.
If that happens, Mr. Kim said, he has “no plan” on where to go — just like the desperate family in “Parasite,” which became the first foreign-language movie to win the Academy Award for Best Film this month.
Overseas, South Korea may be best associated with its Samsung smartphones, Hyundai cars and K-pop stars like BTS.
But “Parasite” has mesmerized viewers around the world by exposing a much grimmer side of South Korea’s economic growth: urban poverty, and the humiliation and class strife it has spawned.
The movie does so through the tale of a family in Seoul who lives in a “banjiha,” or a semi-basement home like Mr. Kim’s, and whose initially hilarious subterfuge to latch onto a wealthy family unravels tragically.
The fictionalized story reflects the lives of Seoul’s so-called dirt spoons, the urban poor, many of whom live in semi-basements in the congested city, where living high and dry — in apartment towers and away from the honking, yelling and odoriferous squalor of down below — symbolizes the wealth and status of the gold-spoon class.
In Seoul, where housing prices have been rising fast, many students and young couples start out renting in a banjiha, with the hope that enough striving and toil will eventually lead to homeownership in an apartment tower.
“It’s clearly a basement but people living there want to believe they belong to the above-the-ground world,” the director of “Parasite,” Bong Joon-ho, said last year at a news conference in with South Korean Media after his film was invited to the Cannes Film Festival. “They live with constant fear that if things get any worse, they will be completely swallowed underground.”
While younger banjiha occupants may dream of escape, many others are elderly or unemployed people who have all but abandoned hope for social mobility. They live hand-to-mouth, one step away from becoming homeless.
Hundreds of thousands of people live semi-underground in Seoul, scattered around the city, according to government statistics. They remain largely invisible unless you explore back alleys at night and see their lit windows below street level. Many live, literally, in the long shadows of shopping and apartment towers.
Even before “Parasite” won the Oscar, local movie fans and foreign tourists had begun visiting the locations where some of the film was shot, to sample the sights and smells of the real-life Seoul that inspired the story.
They visit Ahyeon-dong, a hillside shantytown covered with identical two- or three-story tenements. The cheapest rooms are available in semi-basements there for $250 to $420 a month.
During a recent visit, “Piggy Super,” a grocery store that appeared in the movie under a different name, offered no fresh meat but was selling plenty of dried fish, liquor and other cheap fare. A man stepped in from the evening cold and bought some instant noodles and an egg for dinner.
“He is O.K.,” said the store’s owner, Kim Kyong-soon, 72, looking at the man’s back. “Unlike others, he doesn’t cheat when he counts out his coins.”
A warren of narrow alleyways stretch uphill around the grocery store, many ending in steep stairs.
This is the neighborhood of Mr. Kim, the taxi driver. Just outside his door on a recent night, under a streetlight, a neighbor sorted piles of empty paper boxes and other trash she collects for a living.
When Mr. Kim climbs out of his den, he sees a view of tall, sleek, brightly lit apartment blocks looming in the distance like a mirage.
“They keep going higher and higher, so they won’t have to smell the smell down below,” Mr. Kim said of the tower dwellers. “Those living up there must look down on people like me like pigs.”
In Seoul, wealth is measured by how high you live, said Kim Nam-sik, a real estate agent in Seoul’s quiet Seongbuk district, home to dozens of foreign ambassadors’ residences and where the rich family of “Parasite” lives.
“The taller your apartment tower and the higher floor you live on in the tower, the more expensive your apartment,” he said.
Many of the richest of the rich in Seongbuk, like the family in “Parasite,” live in luxurious, multimillion dollar, single-family homes with large backyards, shaded by graceful pine trees. These islands of affluence are secluded behind imposing walls topped with spikes and security cameras.
Many of the homes also have underground spaces, originally built as air-raid shelters where the owners stocked emergency food in case North Korea invaded. Now, these hideaways, one of which plays a central role in the movie’s plot, are used mainly as underground gyms and home theaters.
Fear of war with the North is also one of the reasons there are so many basement homes in Seoul’s poor districts.
During the Cold War, the government encouraged the building of underground shelters. But as the city’s population exploded to 10 million in 1990, from 1.5 million in 1955, the authorities allowed landlords to rent out the underground space to rural South Koreans like Mr. Kim, who migrated to Seoul en masse when the economy started galloping five decades ago.
But as the economy slowed and income inequality deepened in later decades, the city’s down-and-out remained stuck underground.
Mr. Kim lives in a four-story tenement building owned by a rich absentee landlord. Six families live in the upper three floors.
Mr. Kim sounded proud when he said that as meager as his home might be, he was better off than the other three families squeezed into the cheapest semi-basement floor. While the other three are renters, Mr. Kim owns his place in the building, bought for $30,000 after he sold his house in a better neighborhood 20 years ago to help pay for his late wife’s cancer bills.
Still, Mr. Kim said that when he goes to his high school reunions, he doesn’t reveal where he lives for fear his friends might pity him.
His worst fear is that he’ll be asked to move out and have to join a growing number of people who live in “gosiwon” or “jjokbang” — flop houses where occupants pay daily or weekly rents for windowless rooms barely enough to squeeze in a bed. There, they often wait there for lonely death.
Mr. Kim said he saw neighbors leave in tears when they were forced to move out from their underground homes.
For now, Mr. Kim said he tries not to think about the future because doing so doesn’t solve anything.
“You will get sick if you get constantly envious of what you can’t have,” he said. “Instead, I try to be as positive as I can, thankful for what I have. I try to keep the dignity of a hard-working man.”
Su-Hyun Lee contributed reporting from Seoul.