As the genre continues to globalise, the girl group has become part of a growing conversation about the definition of K-pop - and whether they fall within those lines.

However, we saw the opportunity in the expanding K-pop market," Philip YJ Yoon, managing director at DR Music, told the BBC.

Korean has different speech forms, depending on the listeners' age, social status, level of intimacy and occasions.

Freelance casting director In Ji-woong, who has spent eight years as a choreographer for K-pop groups, says he has heard of foreign trainees escaping from their shared house to go clubbing.

In 2019, K-pop stars Sulli and her close friend Goo Hara passed away in a month - both suspected suicides.

"Dealing with mental stress was the most challenging part for me," says Fatou, who has suffered from depression symptoms since a young age.

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