Growing up in a military family, Yeon-su was taught that the South was the enemy. When she escaped, she tried to stay away from South Korean culture. But music found its way into his life.

He achieved it in 2011, before BTS debuted, before K-pop became a global sensation. Now, even listening to or watching programs from the South is a crime in North Korea that can land people in jail or worse.

Some, like Yeon-su, say they had never heard South Korean music until they crossed the border. When they did, a whole world of freedom and fun opened up, helping them adjust to a strange new life that was now completely theirs.

But other defectors tell the BBC that despite the restrictions, K-pop has managed to make its way into Kim Jong Un’s suffocating dictatorship.

They say they used to listen to songs secretly, often not knowing who they were listening to, but clinging to the mysterious and hopeful lyrics. Some even managed to watch K-pop performances, surprised by the blue-haired idols in makeup: “Why do men look like that?”

“North Korea is a place where the entire system is set up so that there can only be one celebrity, one idol: Kim Jong Un,” says Hannah Oh, a 25-year-old defector.

But it turns out that North Koreans have discovered other idols, such as BTS and Blackpink, and before them, Girls’ Generation, Teen Top and 2PM.

BTS’s Korean name, Bangtan Sonyeondan, has even become part of everyday slang in the North, says one defector: “People say things like, ‘Have you tried on a Bangtan vest?’ or ‘Have you used a Bangtan backpack?'”