Jilin, China (CNN)Wearing big black headphones and sitting on a blue floral bedspread, North Korean defector Lee Yumi was video chatting with yet another stranger online, dark rings shading the pale skin under her eyes.The blurred faces of the two women who escaped from cybersex slavery. Escape from North Korea There are no official statistics showing exactly how many North Koreans have fled their country, which is home to about 25 million people. South Korea says it has welcomed more than 32,000 defectors since 1998. Last year alone, the country received 1,137 defectors -- and 85% of them were women. "It is much easier for them to flee, because they are not usually enrolled in formal employment at a factory or a state firm where any absence would be immediately reported," said Yeo Sang Yoon, from the Database Center for North Korean Human Rights, an NGO in Seoul. "They are in charge of the household and can thus slip away unnoticed." Lee grew up in a family of low-level party cadres in North Korea. "We had enough food," she said. "We even had rice and wheat stored in the garage." But Lee felt her parents were too strict. "I had to be home before sundown, and they didn't allow me to study medicine." One day, after getting into a fight with them, she decided to cross the border into China. Lee said she found a broker to facilitate the dangerous move who promised her a job in a restaurant. That promise turned out to be a lie. Usually, women like Lee pay brokers $500 to $1,000 to organize their safe passage to China, according to NGOs and defector accounts. To reach China, many defectors cross the Tumen River that separates North Korea from China on foot at night, sometimes in freezing weather with the water coming up to their shoulders. After Kim Jong Un came to power in 2011, border security was tightened to avoid the bad publicity associated with defections and prevent information about North Korea trickling into the country, according to Tim Peters, an American pastor who co-founded an NGO called Helping Hands that helps defectors flee. An electric fence was added, as well as cameras at the border. "On the Chinese side, patrols were also increased because Beijing is afraid an influx of refugees could destabilize its own regime," he added. North Korea is visible from Yanji in China. Two huge portraits of Kim Il Sung and Kim Jong Il hang at the entrance of a bridge linking the two countries. Once on Chinese soil, defectors must reach the city of Tumen that sits right up against the icy river, in a lunar landscape of barren hills. North Korea is visible from the town -- farmers in a village there can be seen plowing their fields with antique machinery. Lee crossed the Tumen River in a group of eight girls. When she arrived in China, Lee said she was taken to a apartment on the fourth floor of a pale yellow building in Yanji, a city in Jilin province about 50 kilometers from Tumen, where most signs are written in Korean and Chinese and scores of restaurants sell bibimbap and kimchi, due to the large population of ethnic Koreans. Many of the women working in the city's numerous K-TV and cybersex chatrooms are North Korean defectors. CNN reached out to the platform to ask what steps it takes to protect women like Lee and Kwang on its site, but the company did not respond. "Some of the men just wanted to talk, but most wanted more," said Lee, with a shudder of disgust. "They would ask me to take suggestive poses or to undress and touch myself. I had to do everything they asked." "I felt like dying 1,000 times, but I couldn't even kill myself as the boss was always watching us," she said. Her captor was a man of South Korean descent who slept in the living room to keep a close eye on the women. "The front door was always locked from the outside and there was no handle on the inside," said Kwang. "Every six months, he would take us out to the park." On this small patch of green next to their apartment, retirees would meet to dance to music each afternoon. Pastor Chun Ki-Won has been helping North Korean defectors flee for 20 years. He has been nicknamed the Asian Schindler. Chun, a mild-mannered man with high cheekbones and wavy gray hair, is one of a band of Korean pastors who specialize in helping North Korean women escape from China. Chun said his Christian aid organization, Durihana, has helped over 1,000 defectors reach Seoul since 1999. Korean media has nicknamed him the Asian Schindler, after the German industrialist and Nazi Party member who saved the lives of 1,200 Jews. "In the past few years, dozens of missionaries linked to my organization have been deported from China," he said from his Seoul office that overflowed with plants, books and religious figurines. "There are only a few left, and they have to stay on the move constantly to avoid being arrested." China is a close ally of Pyongyang and doesn't consider North Korean defectors refugees, instead seeing them as illegal economic migrants. "When it catches them, it sends them back (to North Korea), where they face torture, internment in a labor camp and sometimes death," said Lee Eunkoo, the co-founder of Teach North Korean Refugees, an NGO that helps defectors learn English. In September 2018, Lee contacted Pastor Chun on KakaoTalk, a Korean messaging service. "Hi, I want to go to South Korea. Can you help me?" read the first message she sent. Over the following weeks, Lee explained to Chun how she had ended up in a cybersex chatroom. He asked her about the apartment's layout and her boss' comings and goings. By mid-October a plan had been hatched: Chun would send a team to Yanji to extract Lee and Kwang. Lee Yumi and Kwang Ha-Yoon have just arrived in the capital of a Southeast Asian country, after crossing the border with China on foot illegally. They have been traveling for 50 hours. After escaping Yanji, Lee and Kwang said they went across China on buses and trains using fake Korean passports. Their last stop was Kunming, in China's deep southwest. From there, most defectors cross the border illegally into Laos or Myanmar and either head for the South Korean Embassy in the capital cities of those countries, or continue to Bangkok, in Thailand. CNN has not revealed which country Lee and Kwang traveled to for security reasons. Lee and Kwang met with a Chinese man who took them across the mountains into a neighboring country. "We walked for five hours through the jungle, before reaching a road where a car was waiting for us," said Kwang. Chun later met them in the middle of the night on the side of a road. "I burst into tears as soon as I saw him," said Kwang, who is now 24 years old. "For the first time in a very long time, I felt safe." After two more days of traveling by car and bus, they reached the capital city. "We were stopped several times by the police for routine checks, I was terrified," said Kwang. In total, they said their journey from Kunming took 50 hours. As they rode towards the embassy in a tuk tuk, Lee stared giddily at the urban landscape unfolding before her eyes. "I'm so happy!" she said, as the embassy approached. Kwang was more nervous. "I know I should feel joy, but I just feel empty," she said. "I don't know what to expect, and I am afraid of the interrogations at the embassy."