By John Ruwitch and Joseph CampbellNINGBO, China (Reuters) - Two days before they sought asylum in South Korea, the North Korean waitresses in the Chinese coastal city of Ningbo shopped for backpacks at a nearby store and paid relatively expensive full prices."I asked them 'Are you going on a trip'', and they said yes," said one of the workers at the shop, who declined to give his name. "They seemed happy."Another shop worker, surnamed Gong, confirmed the story.Four waitresses from the Ryugyong Korean Restaurant visited the nearby store on April 5 and bought three backpacks, each for the listed 199 yuan (about $31), even though they were often known to bargain, the workers said.Two days later, 12 of the restaurant's waitresses and one manager arrived in Seoul, the South Korean capital, in the biggest mass defection case involving North Koreans in several years.How they planned and executed their trip remains a mystery.South Korea has only said it has admitted 13 defectors, North Korean restaurant workers who arrived on April 7, on humanitarian grounds. The North has called it a "hideous" abduction of its workers by the South.China has said a group of 13 North Koreans used valid passports to leave the country normally on April 6, but did not say where they went.In Ningbo, shopkeepers nearby considered the North Korean restaurant and its pretty but secretive waitresses a curiosity.The restaurant, now closed, sits on a newly developed pedestrian street for tourists that opened for business in late September last year.Across the lane at a cosmetics shop, Jiang Jiang recalled the noisy, patriotic North Korean music sung by the waitresses, a routine deployed at many of the around 130 North Korean restaurants around the world. Most remit revenues back to Pyongyang."Not my style," she said. Moving her computer cursor between April 5 and 6 on a calendar, she added: "This is about when I stopped hearing the music. It was really loud music."Some shopkeepers nearby said the restaurant appeared to have been closed for renovations several months ago, but stories varied. Business did not appear to be great.An employee of the company that manages the vintage-looking grey brick and wood buildings that line the pedestrian street, including the Ryugyong, said the workers were very secretive, and generally only seen outside when they were coming to and from work."They were under military-like management, and not free to go anywhere," she said. Shopkeepers said sometimes they would shop for small items like hair bands.Typically, North Koreans working overseas are chosen for their loyalty but are subject to many restrictions. They usually live together and are guarded by security officials.Xue Bin, one of the Chinese businessmen behind the restaurant, said he pulled out of the venture after a disagreement with a partner about six months ago.Corporate records indicate that Xue is the legal representative of the venture, which is wholly owned by a man named Wang Qianqian. Wang declined to comment when reached by phone.Xue confirmed that all the workers were imported from North Korea via Korean businessmen. Their salaries were paid directly to the workers in half-yearly increments. The North Koreans lived in a dormitory and were provided food, he said."We provided good conditions," he said by telephone from Beijing. "They had enough food. They had enough free time."Xue declined to say what the business disagreement had been about. He also said he had no idea how the staff had defected."Maybe they paid someone. I don't know," he said.(Editing by Raju Gopalakrishnan)Join the conversation about this story Click here to read full news..