Bong Joon Ho, visionary director of “Parasite,” is a bona fide celebrity in his home country of South Korea, but he still prefers to do his writing tucked in the corner of a coffee shop. Sometimes he has headphones on to concentrate better on a thematic flight of fancy, but some-times, he says, he’ll hear a conversation at an adjacent table and feel the need to eavesdrop.

To retreat into a private vision or to connect with real life: “Parasite” is the marriage of competing impulses. It’s both an auteur project, presenting a hermetic world where Bong had his hand in every detail, and a sharply observed satire of capitalism, classism and inequality.

Bong’s films match a boldness of vision and filmmaking mastery with insight into present-day political unrest. With them, the man referred to as “Director Bong” has clearly entered the pantheon of great modern filmmakers.

Bong’s cinematic education began early. “I was a film geek,” he says. As a youth, he discovered the American Forces Korea Network, which showed movies on Friday and Saturday nights. “It was the 1970s, and Korea was under military dictatorship,” he says. “It was a very conservative mood, but on Friday night we could see some sex and violence. I was a little kid, but I came out to the living room by myself when my family was sleeping and watched those movies.” He loved the American studio films of the era but also “many B pictures,” those more committed to great story­telling than prestige or polish.

Three of his own movies — “Okja,” “Snowpiercer” and “The Host” — are recognizable as, respectively, an adventure story, a science-fiction dystopia and a monster movie, but Bong mashes up genres in unexpected ways. He rearranges seem­ingly familiar story beats with a watchmaker’s precision and an undercurrent of pitch-black humor, so his films add up to much more than their individual style elements.

“I always try to familiarize myself with genre conventions,” Bong says. “I feel more excitement when I break genre conventions and subvert them — but in order to break the rules, you need to be aware of the rules.”
He recognizes “Parasite” as a kind of genre film, “but [it’s one that] talks about our current reality.”

It’s a literal upstairs/downstairs fable that compares the plight of two families on either side of Seoul’s class divide, linking them in a kind of grand battle royale. Its astonishing success in the U.S., France, Denmark, Japan — pretty much everywhere — suggests the film’s despair over class inequality is a global occurrence.

“This time, I didn’t want to tell the story in a sci-fi format,” Bong says. “I wanted it to feel like a story that surrounds us on a daily basis, something more realistic and natural.” One could say it’s almost like something overheard in a coffee shop.

For “Parasite,” he adds, “the story began with the concept of infiltration in itself, this idea of a family of four, a poor family, infiltrating a rich house one by one, like how a parasite would infiltrate a host. And so the idea began with two families — one rich, one poor, each with four members — and the poor sort of seeping into the lives of the rich. I was very excited by that idea.”

From that seed came an idea that Bong couldn’t shake. “The first image I thought of for ‘Parasite’ was the window in the semi-basement home where this poor family is enjoying a meal, and they see a man urinating on the street outside, which brings them a lot of fear.”

Bong methodically controls every step of the filmmaking process. He storyboards meticulously, and on “Parasite” he recognized that the story depended on creating the perfect houses for the two families. “Because I’m so obsessed with space,” he says, “usually I spend a long time location scouting. I’m very persistent with finding the spaces, but because with ‘Parasite,’ 90% of the story happens in the two houses, we built the sets from scratch.”

The director knows that even a con­structed set is never a perfectly controlled envi­ron­ment, and no matter how inventive Bong’s staging, the success of his films depends largely on his work with actors. “My priority is always to make my actors feel comfortable and free,” he says, “but at the same time I have this desire to have full mastery over the space and control even the tiniest increments, like half an inch. So I have these two contradicting desires.” He has even been known to show performers a storyboarded version of a shot before they step into the scene.

Even the cast of “Parasite” finds Bong enigmatic. Choi Woo Shik, who plays the son of the poor but devious Kim family, calls Bong “a truly mysterious person.” Lee Jung Eun, who plays the housekeeper the Kims displace, says, “Director Bong is very funny and weird. He is always the same and only thinks about film all day.”

Bong meticulously storyboards his films. In this scene, the increasingly desperate Kims, who live in a space lower than their toilet, are perched at their commode to try and get free Wi-Fi.

“On the set,” says Choi, “I hear more casual everyday talk or funny stories [from him] than comments about the actual film. But at the same time, he is extremely sharp. He seems to know the limits to an actor and helps his charms pop out.”

The smash success of “Parasite” coincides with the centennial of Korean film, which began with the 1919 movie “Fight for Justice.” Says Bong, “Korean cinema has a long history, and there are many masters that have yet to be introduced to the Western audience.”

Bong is not fluent in English, but undeniable command of his medium, combining a careful deployment of special effects with a canny, ground-level understanding of human behavior, has made him one of the world’s most influential auteurs. His cinematic universe is a richly imag-ined, obsessively detailed environment — an environment that feels frighteningly real.