They wear the unofficial uniform of a billion other young people: jeans, T-shirts and sneakers. But until recently, these Seoul students had never heard rap music, eaten a burger or watched David Beckham dribble a ball.
Born in the Rip Van Winkle state of North Korea, where Western clothes and culture are restricted or banned, they are now struggling to adapt to life in the noisy, capitalist South says Cho Myung-sook, the vice-president of one of the few schools in the South for Northern defectors.
"They often have a hard time here. They have to be taught to begin again from scratch. Many people don't understand that they are so pure," says Ms Cho. "They have so much sympathy for people who are weaker or in trouble. They often end up in jobs helping others."
Their plight is one of the lesser-known modern tragedies, says Rev Tim Peters, the founder of the Seoul-based humanitarian group Helping Hands Korea. Many have been refugees for months or years. They have no rights. Some have been caught and sent back to prison only to escape again.
Peters says that North Korean agents in the border areas around China co-operate with Chinese security forces to hunt for defectors. Some disguise themselves as refugees or work undercover as employers. If caught and repatriated, North Koreans face prison or worse. Amnesty International says some have been tortured and executed.