South Korean boy band Big Bang are megastars of so-called K-pop. From left, Seungri, T.O.P., G-Dragon, Taeyang and Daesung. (Irwin Wong/for The Washington Post)

They’re one of the biggest boy bands in the world. Their concerts make One Direction’s look poorly attended. Compared with their fans, Beliebers seem halfhearted.

They’re Big Bang, and you’ve probably never heard of them.

For a decade, these five stylish, edgy guys have defined and redefined South Korean pop music. They’ve defied the idea that so-called K-pop is inevitably sugarcoated and factory-produced, and that boy bands are all about pretty faces and lip-synching.

But now, as Big Bang celebrates its 10th anniversary, fans are beginning to deal with the unthinkable: that Big Bang as they know it may not exist for much longer.

Thanks to the threat of North Korea, South Korea still has compulsory military service, requiring all men to complete at least 20 months’ duty before they turn 32.

That means the clock is ticking for Big Bang, which consists of lead singer G-Dragon, who takes his stage name from his Korean given name, Ji-yong (“yong” means “dragon”) and four others who go by the names T.O.P., Taeyang, Daesung and Seungri.

Speculation is rife that T.O.P, who’s 28, could enlist this year, while G-Dragon and Taeyang, both 27, are tipped to enter the military in 2017.

It’s a subject the band doesn’t much like to talk about.

“If we’re going to talk about that, we’ll feel sad,” G-Dragon told The Washington Post in a rare interview in Tokyo while the band was on its M.A.D.E. world tour. “I’m just kidding,” laughed the singer, who was wearing sunglasses and an oversize suit jacket over a purple turtleneck and spoke in fluent, slightly rapper-style English.

But the reality can’t be avoided.

“We are Korean, so we have to go someday, but I don’t know when it’s going to be,” he continued. “Until then, we’ll just try hard to do what we got to do.”

The M.A.D.E. tour ends this weekend in Seoul and has been huge. Big Bang sold 910,000 tickets for 18 concerts in Japan alone. By comparison, Taylor Swift sold almost 2.3 million tickets and One Direction sold 2.4 million on their tours last year – but it took them 83 and 85 shows, respectively.

Big Bang’s tour has included stops in Las Vegas, Los Angeles and New Jersey, as well as Mexico and Canada.

Big Bang performs in Shanghai in June. K-Pop spread across Asia in the 2000s and became a juggernaut encompassing music, movies and even plastic surgery. (Ding zhenjie/Imaginechina)

“We were amazed that people knew our songs in countries that we haven’t even been to, such as in Mexico,” said Taeyang. “They’d never seen us other than on the Internet.”

K-pop took off in the 1990s, when South Korean music companies started putting potential stars on grueling training schedules — living in dorms with no phones or Internet — and churning out highly manufactured groups with a saccharine sound. Vocal talent came second or third to looks and dancing ability.

This style of music became popular in Japan and then, in the 2000s, across Asia, as part of the “Korean wave” of popular culture that also included dramas and movies, as well as fashion and, increasingly, plastic surgery.

In the West, just as Latino music went from fringe to mainstream, so, too, is K-pop breaking out of its niche. Both Spotify and iTunes now list K-pop as genres.

Big Bang performs in the 2012 K-Collection fashion concert in Seoul. (Chung Sung-Jun/Getty Images)
Pushing boundaries

Big Bang emerged from years of training under YG Entertainment, one of South Korea’s top music labels, which also counts Psy of “Gangnam Style” fame among its stars, to make their debut in 2006.

From their origins in the K-pop machine, the band has matured to become a new generation of boy band, one whose artists are involved in writing, composing and producing.

Indeed, they bristle at the label “K-pop.”

“Actually, I don’t know why they call Korean music ‘K-pop,’” Seungri said. “Good music is good music, so if you are going to be doing good music, then they are going to be listening to our music.”

G-Dragon chimed in. “We are Korean, so obviously they call our music K-pop. But we never thought of our music as K-pop. Our music is just our music.”

“It’s like this,” added T.O.P. “You don’t divide pop music by who’s doing it. We don’t say, for instance, ‘white pop’ when white people make music.”

Big Bang at the K-Collection concert: “Of all the mainstream acts, they’re doing the most to push boundaries of what is considered K-pop,” a music journalist says. “The group has been pretty active in trying out all sorts of different stuff.” (Chung Sung-Jun/Getty Images)

Mark James Russell, an entertainment journalist based in Seoul who has written two books about K-pop, said that the band has defied categorization.

“Of all the mainstream acts, they’re doing the most to push boundaries of what is considered K-pop,” said Russell. “The group has been pretty active in trying out all sorts of different stuff.”

Big Bang’s videos, in particular, push those boundaries. The trippy “Bae Bae” has garnered 58 million views on YouTube. (Which may be nothing compared with Justin Bieber and Taylor Swift but is huge for Asia.)

In another innovation, the band released eight singles last year — including “Bang Bang Bang,” “Loser” and “We Like 2 Party” — then put them all out as the “M.A.D.E.” album last month.

“Bang Bang Bang” is so punchy that the South Korean government has been blasting it across the demilitarized zone into North Korea as part of its propaganda war with the communist state.

The band members have “become artistic superheroes,” says a representative of a rival Korean music company, who asked for anonymity because he was talking about a competitor. “They have shown versatility and success in whatever they do.”

Big Bang performs at the closing of the 2014 Asian Games at Incheon Asiad Stadium. (Chung Sung-Jun/Getty Images)
Branding as individuals

But the question of military service continues to hang over the men, and it almost seems as if the band has been preparing for this inevitability, with each member cultivating his own image and all of them marketing themselves as individuals and smaller units.

Taeyang and Daesung both have solo acts planned, while T.O.P. has been concentrating more on acting.

As for G-Dragon, well, G-Dragon is fashion incarnate. He was in the front row of the Chanel show during Paris Fashion Week this year, clad in a Navy-style Chanel suit and a huge black fur hat. When G-Dragon posts a photo of himself, whatever he is wearing usually sells out instantly.

Industry insiders say he has a confidence and swagger that make him appealing, plus a David Beckhamlike ability to look both androgynous and studly at the same time.

So, what happens next? The band members are philosophical about the future. “I believe in destiny, and I’m going to let it flow and see how it goes,” said T.O.P.

But there is a sense, after 10 years, that the thrill of being an idol is wearing off.

“I never got tired of the music thing till now, but we are still young, so we can do whatever we want,” said G-Dragon. “I just want to try something new. That’s my new goal. Like fashionwise, or like whatever.”

But for now, they’re not talking about splitting up. As G-Dragon put it: “Carpe diem, you know.”