Pyongyang, North Korea (CNN) Ri Gum Ryong and his daughter, Ri Ryo Gun, live in Pyongyang.

Their home is a large and modern flat, by North Korean standards. It's sparsely furnished -- not uncommon in North Korea -- but still cozy.

However, there's one notable, painful absence in this immaculately-kept family home: mother and wife Kim Ryon Hui, whom neither husband or daughter have seen for nearly six years.

Kim Ryon Hui is alive and well, and claims she's equally as desperate to be reunited with her family.

However, she's living in South Korea, and while they might only be a 20-minute flight away, in between the two sides of the family lies one of the most insurmountable borders in modern history.

"Today marks the 2,150th day since I was separated from mom," says 23-year-old Ri Ryo Gun, visibly emotional. "Not a day or two -- but six years."

Photos: Inside North Korea North Korean high school students play on a beach at Wonsan, on September 11, 2017. Hide Caption 1 of 101 Photos: Inside North Korea Bartender at the Rainbow floating restaurant in Pyongyang on September 10. Hide Caption 2 of 101 Photos: Inside North Korea Sunday afternoon row boats on the Taedong River, Pyongyang, beside Juche Tower. Taken on September 10. Hide Caption 3 of 101 Photos: Inside North Korea Participation in mass celebrations is mandatory for those privileged citizens allowed to live in the capital, Pyongyang. Taken on September 9. Hide Caption 4 of 101 Photos: Inside North Korea Pyongyang residents walk past a poster marking the 69th DPRK Foundation Day on September 9. It reads "Let the entire world look up to the great Kim Il Sung nation and Kim Jong Il Korea." Hide Caption 5 of 101 Photos: Inside North Korea This statue in Samjiyon depicts North Korea's founding President Kim Il Sung when he was a guerrilla fighter against the Japanese. Taken on September 6. Hide Caption 6 of 101 Photos: Inside North Korea The lobby of the CNN team's hotel in Samjiyon on September 5. Hide Caption 7 of 101 Photos: Inside North Korea A bus driver who drives a Japanese vehicle over some of the bumpiest roads in North Korea. Taken on September 5. Hide Caption 8 of 101 Photos: Inside North Korea Propaganda banners line the streets of Samjiyon on September 4. Hide Caption 9 of 101 Photos: Inside North Korea Public transportation in rural North Korea, near the Chinese border, taken on September 4. Hide Caption 10 of 101 Photos: Inside North Korea A young North Korean musician in the border town of Kaesong, taken on September 4. Music is a huge part of life in North Korea. Hide Caption 11 of 101 Photos: Inside North Korea North Korean tour guide at Mt Paektu outside the alleged birth place of Kim Jong Il, on September 3. Kim is widely considered to have been born in Russia. Hide Caption 12 of 101 Photos: Inside North Korea Housing units deep in rural North Korea, near the border with China, taken on September 3. Hide Caption 13 of 101 Photos: Inside North Korea A boy living in the mountainous northeastern border region on September 3, not far from North Korea's sixth nuclear test. Hide Caption 14 of 101 Photos: Inside North Korea The view from the top of Mt Paektu on September 3, a sacred site to North Koreans close to the border with China. First time CNN has ever been allowed here. Hide Caption 15 of 101 Photos: Inside North Korea The Mausoleum of Tangun is said to hold the remains of the ancient King Tangun -- widely considered a mythical figure.



North Korea built the pyramid in 1994 and has not allowed outside experts to verify the remains inside. Hide Caption 16 of 101 Photos: Inside North Korea Sunset from inside Pyongyang, the North Korean capital, on August 31. Hide Caption 17 of 101 Photos: Inside North Korea The crowd applauds as North Korean TV airs footage of their latest missile launch outside Pyongyang Station on August 30, 2017. Hide Caption 18 of 101 Photos: Inside North Korea The parents in North Korea of an inadvertent defector react to a video message , shared by CNN's Will Ripley, from their daughter, who lives in South Korea and cannot return home. The family hasn't been together in years. Hide Caption 19 of 101 Photos: Inside North Korea May Day celebrations are held on May 1 in Pyongyang. Hide Caption 20 of 101 Photos: Inside North Korea A North Korean boy sits in his family's living room on April 30 in Pyongyang. Hide Caption 21 of 101 Photos: Inside North Korea North Koreans in Pyongyang celebrate the country's 85th annual Army Day on April 25. The holiday celebrates the founding of its army. Hide Caption 22 of 101 Photos: Inside North Korea A North Korea veteran stands against the backdrop of the USS Pueblo, a US Navy ship that North Korea captured in 1968. CNN's Will Ripley‪ asked this veteran about his thoughts on the USS Carl Vinson, an American aircraft carrier conducting joint drills with two Japanese destroyers in the western Pacific Ocean. The veteran told Ripley, "We can sink that aircraft carrier." Hide Caption 23 of 101 Photos: Inside North Korea Ripley noted that in Pyongyang, children are often seen dressed in bright, colorful clothing, contrasting with the more conservative and darker outfits worn by many adults. Hide Caption 24 of 101 Photos: Inside North Korea North Korean soldiers march on April 15, as the nation marks the birth of its founder, Kim Il Sung, who is also the grandfather of current leader Kim Jong Un. Hide Caption 25 of 101 Photos: Inside North Korea North Koreans celebrate the birthday of Kim Il Sung. He would have been 105. Hide Caption 26 of 101 Photos: Inside North Korea Tanks roll through Kim Il Sung Square on April 15. Hide Caption 27 of 101 Photos: Inside North Korea North Korean air force jets fly over the Pyongyang celebration. Hide Caption 28 of 101 Photos: Inside North Korea North Korean leader Kim Jong Un appears at a ceremony to formally open a housing development in Pyongyang on April 13. The project was rushed to completion in under a year, North Korean officials say. Hide Caption 29 of 101 Photos: Inside North Korea North Koreans gather to witness the opening of the Ryomyong Street housing development. Hide Caption 30 of 101 Photos: Inside North Korea Foreign journalists are filmed by North Korean media during the Ryomyong Street event. Hide Caption 31 of 101 Photos: Inside North Korea Soldiers leave the opening ceremony of the Ryomyong Street development. Hide Caption 32 of 101 Photos: Inside North Korea North Koreans observe a statue of their founder, Kim Il Sung, at the Museum of the Korean Revolution on April 10. CNN's Will Ripley said it was the first time CNN cameras had been allowed into the Pyongyang museum. Hide Caption 33 of 101 Photos: Inside North Korea North Koreans pose on April 9, for a photo at Mangyongdae, the birthplace of Kim Il Sung. Hide Caption 34 of 101 Photos: Inside North Korea Boys in Pyongyang pose for a photo at a secondary school for orphans on February 19. Hide Caption 35 of 101 Photos: Inside North Korea A tiger is seen at a zoo in Pyongyang on February 19. CNN's Will Ripley, Tim Schwarz and Justin Robertson were the only Western broadcasters reporting from North Korea after it conducted a ballistic missile test on February 12. See their dispatches Hide Caption 36 of 101 Photos: Inside North Korea CNN's Will Ripley posted this photo of the Pyongyang skyline on February 17. "Note the 105-story pyramid skyscraper, the Ryugyong Hotel. Work began in 1987. Still unfinished," Ripley said in his Instagram post. Hide Caption 37 of 101 Photos: Inside North Korea North Korean soldiers ride on February 17, in a black Mercedes-Benz on the streets of Pyongyang. Hide Caption 38 of 101 Photos: Inside North Korea A 70-story apartment building undergoes construction on February 17. Hide Caption 39 of 101 Photos: Inside North Korea The floating Rainbow Restaurant is seen in Pyongyang on February 17. Hide Caption 40 of 101 Photos: Inside North Korea North Korean soldiers watch fireworks on February 16, in Pyongyang. Hide Caption 41 of 101 Photos: Inside North Korea People use smartphones on on February 16, to take photos of an ice sculpture in Pyongyang. Hide Caption 42 of 101 Photos: Inside North Korea A soldier stands guard in North Korea on February 16. While military service for women has long been voluntary, it reportedly was made mandatory recently in a bid to bolster the armed forces. Hide Caption 43 of 101 Photos: Inside North Korea A boy visits the Kimjongilia flower show on February 16. The red flowers are named after the late North Korean leader Kim Jong Il. Hide Caption 44 of 101 Photos: Inside North Korea University students dance in front of the Pyongyang indoor stadium on February 16. Hide Caption 45 of 101 Photos: Inside North Korea Book titles are listed in English at a bookshop for tourists in the Yanggakdo Hotel in Pyongyang. Hide Caption 46 of 101 Photos: Inside North Korea Ice flows down the Taedong River in Pyongyang on February 16. Hide Caption 47 of 101 Photos: Inside North Korea Soldiers pay respects to former North Korean leaders on February 15. The site is considered one of the most sacred in Pyongyang. Hide Caption 48 of 101 Photos: Inside North Korea Vendors sell flowers February 15 to mourners paying their respects to deceased leaders of North Korea. Hide Caption 49 of 101 Photos: Inside North Korea The view over the frozen Taedong River shows residential areas of Pyongyang on February 15. Hide Caption 50 of 101 Photos: Inside North Korea The symbol of North Korea's sole political party, the Korean Workers' Party, can be seen atop a government building in Pyongyang. Hide Caption 51 of 101 Photos: Inside North Korea Taxis are becoming more prevalent on the streets of Pyongyang. Most commuters still ride buses. Hide Caption 52 of 101 Photos: Inside North Korea Tour guides told CNN's crew that "in 1948, Kim Il Sung, his wife and his then 7-year-old son, Kim Jong Il, test fired North Korea's first domestically manufactured submachine gun," Tim Schwartz said on Instagram. The guides said that all three shot bullseyes at 50 meters. Hide Caption 53 of 101 Photos: Inside North Korea The Man Gyong Dae School Children's Palace, shown in May 2016, is an after-school activity complex in Pyongyang. Hide Caption 54 of 101 Photos: Inside North Korea Young singers practice their performance at a "children's palace" in Pyongyang. Hide Caption 55 of 101 Photos: Inside North Korea Children play volleyball at an after-school center in Pyongyang. Hide Caption 56 of 101 Photos: Inside North Korea An Olympic-sized swimming pool is a focal point of a "children's palace" after-school center in Pyongyang. Hide Caption 57 of 101 Photos: Inside North Korea Pyongyang prepares in 2016 for the Workers' Party of Korea congress, the first such meeting since 1980. The event aimed to consolidate Kim Jong Un's power in the regime. Hide Caption 58 of 101 Photos: Inside North Korea A train can be seen from the window of the Koryo Hotel in Pyongyang. Hide Caption 59 of 101 Photos: Inside North Korea CNN visits the North Korean Science and Technology Center in Pyongyang in January 2016. Hide Caption 60 of 101 Photos: Inside North Korea Visitors to North Korea's Science and Technology Center use the tightly regulated North Korean intranet. Hide Caption 61 of 101 Photos: Inside North Korea A guide shows visitors a display in the North Korean Science and Technology Center. Hide Caption 62 of 101 Photos: Inside North Korea Exhibits at the North Korean Science and Technology Center include this fighter jet. Hide Caption 63 of 101 Photos: Inside North Korea During a carefully choreographed show of strength to mark the 70th anniversary of the ruling Korean Workers' Party in October 2015, a soldier marches across Pyongyang's Kim Il Sung Square. Hide Caption 64 of 101 Photos: Inside North Korea Young members of North Korea's military ride artillery through Pyongyang. Hide Caption 65 of 101 Photos: Inside North Korea North Korean soldiers march below statues of North Korea's founding president Kim Il Sung and his son, Kim Jong Il. Hide Caption 66 of 101 Photos: Inside North Korea Weapons are paraded through Pyongyang as a clear signal to the rest of the world that North Korea has military might. Hide Caption 67 of 101 Photos: Inside North Korea A large mural of North Korean founder Kim Il Sung stands outside the Jang Chon cooperative farm, a 30-minute drive outside the capital Pyongyang. CNN visited the farm in September 2015. Hide Caption 68 of 101 Photos: Inside North Korea Farm manager Kim Myong Jon is something of a celebrity in North Korea. During the past 40 years, she's met with all three North Korean leaders. Hide Caption 69 of 101 Photos: Inside North Korea The farm where Kim Myong Jon works is home to one of North Korea's first greenhouses. It was first visited by Kim Il Sung more than three decades ago, and more recently by his grandson, current leader Kim Jong Un. Hide Caption 70 of 101 Photos: Inside North Korea Chili peppers lie in the sun at the Jang Chon farm. Peppers are used for making kimchi, the fermented cabbage dish that is a staple of the North Korean diet. Hide Caption 71 of 101 Photos: Inside North Korea CNN's Will Ripley speaks with scientists from North Korea's space agency, the National Aeronautical Development Association (NADA). In September 2015, CNN was given exclusive access to the newly opened satellite control center. Hide Caption 72 of 101 Photos: Inside North Korea The futuristic space center is in a residential area not far from the center of Pyongyang. Hide Caption 73 of 101 Photos: Inside North Korea Two officials walk in the grounds of the space facility. NADA officials told CNN that they had prepared multiple satellites and were in the "final stages of perfecting all operations." Hide Caption 74 of 101 Photos: Inside North Korea Hula hoop diplomacy at a North Korean dolphinarium . CNN video journalist Brad Olson was called on stage to show how it's done."I managed to get three going, much to the delight of the crowd," he said. Hide Caption 75 of 101 Photos: Inside North Korea In May 2015, CNN was given rare access to a faculty apartment in an upscale area of Pyongyang, near Kim Il Sung University. The lounge was neat, if a little dated. Hide Caption 76 of 101 Photos: Inside North Korea This is the master bedroom of the three-bedroom apartment. A university professor lives in the home with his adult children. It's 200 square meters (about 2,150 square feet). That's large for an apartment in Pyongyang. Hide Caption 77 of 101 Photos: Inside North Korea A flat-screen television sits prominently in the lounge. Hide Caption 78 of 101 Photos: Inside North Korea Books are neatly lined up above a desk in the study. There's a lamp for reading and a large padded chair. Hide Caption 79 of 101 Photos: Inside North Korea Every home in North Korea displays portraits of late leaders Kim Il Sung and Kim Jong Il. Housing is assigned by the government and is free. Those who want to move have to sign up to exchange places with other citizens. Hide Caption 80 of 101 Photos: Inside North Korea The kitchen features a double sink and brushed metal counter tops. Hide Caption 81 of 101 Photos: Inside North Korea The kitchen is fitted with a Haier two-burner gas hob. Haier, based in Qingdao, China, is one of the world's biggest home appliance companies. Hide Caption 82 of 101 Photos: Inside North Korea First-graders in a Pyongyang classroom are orderly yet energetic, often standing and giving spirited answers to their teacher's questions. Hide Caption 83 of 101 Photos: Inside North Korea North Korean students watch riding lessons at a new equestrian center designed by Supreme Leader Kim Jong Un. The facility was formerly used for military training. Hide Caption 84 of 101 Photos: Inside North Korea Outdoor exercise accompanied by upbeat music is a daily routine for these North Korean middle school students. Classes are critiqued on their coordination. Hide Caption 85 of 101 Photos: Inside North Korea Young children in a newly constructed Pyongyang orphanage practice a musical performance. Hide Caption 86 of 101 Photos: Inside North Korea The orphanage features a pool area for the children, who live and study in the complex. Hide Caption 87 of 101 Photos: Inside North Korea Young boys practice a drum routine that they will perform during International Children's Day. Hide Caption 88 of 101 Photos: Inside North Korea Toy rocket launchers sit ready for children to play with. Hide Caption 89 of 101 Photos: Inside North Korea Junior Lt. Col. Nam Dong Ho speaks to CNN correspondent Will Ripley. In May 2015, Ripley and his team were granted rare access to the Demilitarized Zone (DMZ) in North Korea. An estimated three-quarters of North Korea's standing army of more than a million is based near the heavily fortified border. Hide Caption 90 of 101 Photos: Inside North Korea Soldiers stand guard on the North Korean side of the DMZ. Hide Caption 91 of 101 Photos: Inside North Korea North Korea displays the armistice agreement that brought the brutal fighting of the Korean War to an end in 1953. Hide Caption 92 of 101 Photos: Inside North Korea Junior Lt. Col. Nam Dong Ho is part of North Korea's standing army of more than a million. Hide Caption 93 of 101 Photos: Inside North Korea Pyongyang women wear their Sunday best -- and carry ornate umbrellas to shield themselves from the sun. Hide Caption 94 of 101 Photos: Inside North Korea Twin statues honor the late leaders of North Korea, Kim Il Sung and Kim Jong Il. Visitors to Pyongyang are routinely taken to pay their respects and lay flowers at the monument. Hide Caption 95 of 101 Photos: Inside North Korea Kim Jong Un personally inspected the plans for this new water park and had his top officials test the water slides for safety. Hide Caption 96 of 101 Photos: Inside North Korea Visitors to a Pyongyang water park play table tennis. Hide Caption 97 of 101 Photos: Inside North Korea The Pyongyang Gold Lane, a bowling alley in the North Korean capital, is popular among young people. Hide Caption 98 of 101 Photos: Inside North Korea Pyongyang Airport is the first stop on tours of North Korea. Air Koryo is the national airline. It operates direct flights from Beijing and Shenyang in China, and Vladivostok in Russia. Air Koryo has an aging fleet, although it has purchased some newer aircraft in recent years. Hide Caption 99 of 101 Photos: Inside North Korea The inflight magazine features multiple pages on Supreme Leader Kim Jong Un. Hide Caption 100 of 101 Photos: Inside North Korea The inflight meal consists of a burger and a glass of North Korean beer. Hide Caption 101 of 101

One-way ticket

Ri's mother, Kim Ryon Hui, lived a relatively upscale life in North Korea until she went to China in 2011 to visit relatives and seek medical care for liver disease. She'd been hospitalized for six months in North Korea and had heard the treatment there was more advanced.

When she arrived, she discovered that Chinese doctors wanted cash for treatment up front and she couldn't afford the medical bills.

China regards North Koreans as economic migrants rather than refugees or defectors, and if they're caught they're usually sent back to face punishment. However, a broker told her that Chinese people often went to South Korea to work, so she decided to do the same.

She says that little did she know, once she signed papers renouncing her North Korean citizenship, she'd never be able to go home. Once she realized this was the case, she told the broker handling her case that she wanted to escape, she says, but the broker took her passport away.

"Other defectors who were with me said if I go out and get caught they too will be handed over to China's Public Security and their life will be in jeopardy. Because I didn't have a passport, I had to follow them and I ended up in South Korea," she told CNN.

Kim says once in South Korea, she turned herself over to the police, pretending to be a spy in hope of being deported. But instead, she ended up in jail, sentenced for two years for passport fraud and espionage.

Visits and letters to the North are permitted, but only with the approval of South Korea's Minister of Unification, and her status as a criminal now makes any travel out of the country impossible.

Without government approval, the South Korean National Security Act stipulates that any contact or correspondence with what it defines as "a member of an anti-government organization" can result in up to 10 years' imprisonment.

This has been the case for tens of thousands of North Koreans who have fled to South Korea since the great famine of the late 1990s -- but Kim is one of the few who says she wants to return.

Video messages

In Seoul, we play Kim a video of her family in North Korea -- a rare opportunity for her to see her daughter who was just 17 when they were separated.

"I'm sorry for keep on crying, when I have to be strong in front of you," Kim's daughter Ri Ryo Gun says in the message.

Ri Ryo Gun, 23, has just graduated from catering college and got her first job in a restaurant.

Ri and her father, Kim's husband, tell her they have received a "great new house." "We hung the family photo and wait for the day you come back," he says.

It amazes Kim how adult her daughter, who has graduated from catering college, has become.

"She was a just a child playing in my arms and that's how I still remember her," Kim says through the tears, adding that she's "so thankful she has grown up to be a bright, confident young woman."

Kim says she takes comfort in the fact her husband and daughter are still young, but what really breaks her heart is being separated from her parents.

"During these six years my father has become an old man that I can't even recognize," she says when we play her a video message from them.

Kim Ryon Hui watches videos from her family in the North.

A bruised heart

Kim's father, Kim Se Hwam, and mother, Jo Won Hui, are both in their 70s.

Jo's eyesight is failing; she's already lost vision in one eye and is losing sight in the other. "What do we do if the daughter comes back when she can't see at all?" says her husband.

The elderly couple live on the 13th floor of an apartment block in Pyongyang. Because the lift is broken, they have to take the stairs.

They say they've received support from friends and the local community, insisting that in their country they "share sadness and tragedy."

But they say their health has suffered from the anguish they feel being separated from their daughter.

"My heart's been bruised," says Kim's mother. "My daughter asked me to stay healthy and please be there to hug me when she comes back, to please give her a hug, but what would it be like for her if she comes back after I pass away?"

We play them a video message and they say it's the first time they've laid eyes on her in six years.

"My aged parents, who should be just spending their last days looking at happiness of their children, and the oldest daughter is still making you sad, making you shed tears. I am so sorry," Kim says in a video message from across the border.

Defections

Previous defectors have said that relatives left behind can bear the brunt of their decision to escape the regime. Some have been sent to prison camps as punishment or are threatened with harm, according to one high-profile defector.

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Kim's family deny this is the case, calling such stories "propaganda" and "rumors."

"There is no such thing as the government punishing us or looking at us differently. They would rather try to help us as much as they can," Kim's father says.

But for daughter Ri, ongoing tension on the divided Korean Peninsula isn't what matters.

"Putting all the politics and ideology aside," she asks, "as a human with love and affection, isn't a heart of a mother who wants to go back to her family, a heart of a person missing his or her parent, a basic right a human must have?"