In an unassuming residential street in the heart of Seoul sits a new popular gathering place for South Korea’s most fashionable people. But the spot isn’t just any fancy cafe or shop locally trending on Instagram — it’s a much more secretive and exclusive place reserved only for the region’s top stylists and celebrities in the know.

There’s no question that K-pop’s allure is drawn from the extremely addictive tunes and frighteningly flashy dance moves, but part of it also has to do with these idols’ impeccably dolled-up image. Head-to-toe styling, perfectly set hair, and coordinated outfits are what complete the magic. And while K-pop stars are often seen wearing the latest luxury brands straight from the runway, most groups can’t afford to dress their members — sometimes over a dozen of them — in thousand-dollar outfits all the time. Not even BTS .

Shine’s clients include major music labels who represent the likes of BTS, Big Bang, Blackpink, and many more of Korea’s most successful music groups. With a tight team of five workers, Shine hand-crafts hundreds of outfits per month for K-pop celebrities and their backup dancers.

In a modest space of about 1,500 square feet, Yubong Jung, founder of Shine, orchestrates his team throughout the production process of each piece of clothing. Each worker — who averages an age of well past 60 — has their own desk and dedicated set of tasks. Jung is the patternmaker who draws the blueprint on the starting fabric. Then, a cutter cuts the fabric according to the pattern, and hands the materials to a sewer. Once sewed, another worker attaches hardware like zippers, buttons, and other details. The last person is for the “finisher,” who puts finishing touches like cutting off extra thread, and ironing and steaming the piece before it is delivered.

“There were only a handful of K-pop costume factories before. Now, because there are tens of dozens of groups with many more members, these types of factories have multiplied in number,” Jung explained. “They’re mostly concentrated around [the neighborhoods] Sinsa, Apgujeong and Dongdaemun.”

Custom-making K-pop clothes began in the early 1990’s, with the debut of Seo Taiji and Boys, who are credited as Korea’s first idol group. Jung, who started his career as a tailor in 1982, has been at the center of K-pop fashion since the beginning.

But despite being in one of the most commercial and touristy areas of the country, one could not easily spot Shine just by looking on the street. It is on the second floor of a nondescript building, with a realtor office on the ground floor, and no signage. Because Shine’s clients are such superstars, it has to adhere to a high level of secrecy and privacy.

Shine is situated in Sinsa, one of Seoul’s most bustling shopping districts; Apgujeong is the city’s luxury mecca (dubbed “Rodeo Drive”), and Dongdaemun is home to most of Seoul’s largest wholesale fashion markets. It’s only natural for celebrity clothing makers to be in such specialized areas: they’re where celebrity stylists and wardrobe managers are concentrated.

The price of one K-pop outfit can range anywhere between $400 to over $900, depending on its design details. Shine does not provide the starting materials and only deals with production. This means that each K-pop idol’s agency or stylist has to source the fabric and hardware themselves. Shine’s door is constantly open with dozens of couriers and messengers delivering fabric for them throughout the day. K-pop agencies request not only stage clothing, but also custom suits, or outfits for advertisements.

After honing his skills and network at his brother-in-law’s celebrity clothing workshop, Chung Hwa Sa, Jung branched out on his own and founded Shine two years ago. Jung took with him many of the workers from Chung Hwa Sa, who have now worked together for over 20 years. When asked if he plans on training new and younger workers, Jung shook his head. “Young people these days don’t want to do this work. It isn’t glamorous or especially honorable.”