Seoul (AFP) - "Time to get up girls!" The call comes at 6:00 am as it does every morning, pulling Ray from her bunk bed at the start of another 16-hour day in search of stardom.

Ray and the five other young women sharing a small Seoul apartment make up the K-pop band "Billion" -- which at times can feel like the number of miles they are from achieving their goal.

K-pop glamour has conquered much of Asia and beyond, but for every headlining boy and girl band, there are many more like "Billion" struggling for a break on the margins of South Korea's best-known cultural export.

And that means gruelling days packed with travelling, training, rehearsing, grooming and performing under the watchful eyes of record label minders who push an almost military-like dawn-to-dusk regimen.

The sacrifice is substantial. Holidays are rare, and most live with other band mates in dorm-like apartments provided by their agencies, who decide when they wake up, what they do, when and what they eat and when they go to bed.

"It's really not what it looks like on TV. You have to work incredibly hard just to make a debut," said Ray.

"We're extremely lucky to have made it this far," the 23-year-old rapper told AFP.

"This far" means a debut album released in March, nearly two years after the group was formed.

Even on a day without a booking, they wake up at six, work out for several hours and spend the rest of the day rehearsing dance steps and honing singing skills, with a 10 pm lights-out considered an early night.

- 'Bit groggy in the morning' -

"They usually go to bed after midnight, so you can see why they are a bit groggy in the morning," explained Lee Hyo-Jin, as she moved from bed to bed, gently but firmly enforcing the wake-up call.

Lee, 31, is one of a trio of managers running Billion's career and scheduling the daily lives of its members.

The band share two spartan bedrooms -- each with a bunk bed and a third mattress on the floor. There's a makeup cabinet and not much else.

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A piece of paper pinned to the wall carries the hand-written message: "We'll make it! We'll be the best! We'll never get tired!"

There is little time for relationships and none of the six has a current boyfriend, while several say they haven't dated for years.

The only break is given for South Korea's two main holidays, the Lunar New Year and the Chuseok harvest festival, when they can visit their families.

- Missing family and home -

"The band literally is my second family," said Song-Yi, 22, a music major who took time out of college to join "Billion".

"I miss my real family a lot but try to contain that feeling, because I need to focus on this right now," she said.

Fellow member Seul-Gi, 19, was just a high school junior when she was picked up by the agency.

Lee is a key figure in the life of the band members: a manager who is also a dorm matron, confidante, minder and peace-keeper.

She is responsible for keeping everyone on a strict diet of twice-daily meals -- consisting mainly of vegetables and fruits, along with small strips of chicken breast.

Looks are everything in the K-pop world -- for girl- and boy-bands -- and a set of scales squats permanently in the living room of the "Billion" apartment.

"It's difficult, because I really like food. But it's necessary," says lead singer Betty, who sometimes stays awake at night sharing fantasies of favourite foods with her two roommates.

Betty, 21, is 1.6 metres (5ft 2in) tall and weighs 45 kilograms (99 pounds).

K-pop has been criticised for its production-line mentality, churning out similar-sounding, similar looking, similar-moving groups.

Billion are managed by Move Entertainment which is a relative minnow in an industry dominated by three groups -- SM, YG and JYP -- who each employ a small army of producers, choreographers and stylists.

The hunt for talent is extremely competitive and the agencies start recruiting kids as young as 13.

- 'It's a survival tournament' -

Monthly tests are held to evaluate progress and determine who will earn a slot in a band -- a winnowing-out process that all the Billion members went through.

"It's a survival tournament where only the winners move onward," said Billion's lead manager Park In-Seo.

"Launching a pop band is a large investment. You have to look after that," Park said.

Costs vary, but different agencies questioned by AFP said launching a band -- from its creation to a debut album -- required an outlay of anywhere between $500,000 and one million dollars.

More time is devoted to dance practice than anything else -- reflecting the importance placed on immaculately-synchronised choreography.

Hour after draining hour, the Billion girls are taken through the same steps to lock in each minor detail from every hip swivel to finger twirl.

"I know it so well, my body moves by itself once this song plays," said Seul-Gi, referring to "Dancing Alone" -- the main track from their album.

Each of the band members are also encouraged to develop a quirky, "special" skill that they can show off during interviews, such as impersonating various celebrities.

Ray's surprising speciality is animal noises, which the management seems slightly ambivalent about.

"Sometimes they say it's funny and I can try it on air, sometimes they don't," she said.

Billion had hoped the March release of their album would earn them a TV break, but barely a month later South Korea was rocked by the Sewol ferry disaster that killed 300 people -- most of them schoolchildren.

The tragedy plunged the entire country into mourning, resulting in the mass cancellation of concerts and entertainment shows.

- Rain, tiny crowds, bad sound -

But they keep plugging the album at every opportunity, including a low-profile regional qualifier for the 2014 Miss Korea contest at a shopping mall outside Seoul.

Held on a small outdoor stage, in torrential rain, in front of a few dozen damp spectators and with a dodgy sound system, the event was a stern test of the band's ambition and commitment.

But it was one they rose to without complaint, bouncing onto the stage after an uncomfortable three-hour wait under umbrellas.

The performance lasted 10 minutes and was greeted with scattered applause before the band climbed into their minivan for the drive back to Seoul.

The next day will see them perform at a corporate picnic.

It can be a thankless life at times, but Billion stick to their punishing regimen and seem genuinely content with their choice.

"Even if we don't make it, it's worth a try," said Ray.