Seoul, South Korea - Han Hyun-min strides down the runway with an expression of emotionless confidence, before pivoting around in front of the rows of photographers whose cameras click in rapid fire.

Han is 15 and fast becoming a regular on the catwalk, making his third appearance at the recent Seoul Fashion Week - a biannual event for South Korean designers. For one show, Han sported patched jeans and a plaid shirt partially covered by a puffy, silver vest.

The high school student is lanky. He has what Youn Bum, his agent at SF Models, calls a "distinct look", making him a rare commodity in the domestic market - and a victim of prejudice.

Han is his country's first black Korean model.

"People assume I'm a foreigner," says Han, who only speaks the Korean language. "I've gotten used to it."

Then he adds: "But I sometimes feel upset when Korean models backstage at a show don't talk to me because they think I don't understand Korean."

Since his first runway show last year, Han has appeared on Korean television and his Instagram followers have surged to more than 26,000. Fans sometimes approach him on the street and ask to take selfies with him.

He says he appreciates the positive attention, but acknowledges that his success comes on the heels of what is often a "difficult life" for people like him.

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Shifting demographics

Han is coming of age in South Korea, one of the world's most ethnically homogenous countries, as it undergoes the greatest demographic shift in its modern history.

Immigration has brought with it an increase in the number of children who are the offspring of a Korean citizen and foreign national, primarily from Southeast Asia. Close to two million foreigners live in a country of 50 million. The number of multi-ethnic persons is expected to reach 300,000 by 2020, up from 40,000 a decade ago, government statistics show.

Han, born to a Korean mother and Nigerian father, has only ever lived in South Korea. He admits to "not knowing much" about Nigerian culture.

Growing up in Itaewon, a Seoul neighbourhood that's long been an enclave for migrants, Han says he has many friends who are "mixed blood", the literal translation of the Korean term for "biracial".

But that diversity didn't mean that Han was immune from bullying.

"Some classmates used to say things like, 'You have a Korean mum, so why do you look black?'" he recalls. "I got a lot of dirty looks and I felt people were disgusted by me."

But Han says he doesn't dwell on those unpleasant memories, preferring to focus on his budding career instead.

Two years ago, the owner of a PC bang, a type of internet cafe popular with online gamers and where Han says he spends much of his free time, persuaded the teenager to model for a friend's clothing line.

Youn Bum saw some of Han's pictures online and arranged to meet him in person.

"I thought he could look good in a lot of different styles," Youn says. "When I met him I told him to do a test walk down the street and I was immediately struck by his presence."

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'Mixed Blood' and 'Amerasian'

Biracial Koreans have come up against an entrenched concept of what it means to be Korean that's based on a supposed "pure bloodline", Gi-wook Shin, director of the Walter H Shorenstein Asia-Pacific Research Center at Stanford University, tells Al Jazeera.

Shin explains that it's a "myth" that the origin of this understanding of national identity comes from ancient Confucian values, as many South Koreans believe.

Instead, it's the result of a late 19th-century German concept of citizenship that was first adopted by Imperial Japan then reappropriated by Korean nationalists during Japan's colonial rule of the peninsula.

The "uniqueness and purity of a Korean bloodline and nation" are "at the core" of the South Korean state and "mixed blood" people are believed to "contaminate the purity of the Korean nation", Shin says.

He adds that this racism became apparent in the 1950s as the United States began stationing soldiers in South Korea.

There were as many as 40,000 "Amerasians" - offspring of American men and South Korean women - born up until the early 2000s. Many of these births were the result of liaisons with prostitutes who worked in so-called "camp towns" outside US bases.

This is all according to Sajin Kwok, who was part of a research team that submitted a report on these zones to South Korea's National Human Rights Commission in 2003.

Kwok, 41, a US-born Amerasian, says their findings painted a "catastrophic picture" for Amerasians - who grew up in and continued to live in camp towns - due in part to the discrimination they endured, as social outcasts, in schools and in mainstream Korean society.

"Amerasians have suffered from astronomically high rates of suicide, violent death, drug and alcohol abuse, incarceration, homelessness, poverty and debt," Kwok says during a conversation over Skype from his home in Minnesota.

He also says authorities pressured women to abort or hand over their newborns to international adoption agencies in an effort to "eliminate" mixed-race children.

3245Kamra, a US-based organisation representing biracial Korean adoptees, says the majority of children adopted overseas up until 1970 were mixed-race. Bella Dalton, the group's cofounder, estimates that nearly 10,000 children were adopted.

Yun Kang-mo, a policy director at South Korea's Ministry of Gender Equality and Family, acknowledges that in the past, biracial Koreans were "neglected" by the government when the country was very poor and "did not have the resources to care for them".

He adds that at the time, economic development was a higher priority and that these children were in a sense "sacrificed" in favour of it.

READ MORE: The debate over South Korea's 'comfort women'

'Multicultural' children

Faced with the growing number of multi-ethnic births, as well as criticism from the United Nations, terms like "pure blood" and "mixed blood" are no longer used in official and educational materials, although the latter expression is still widely spoken and many Koreans don't see it as a pejorative.

The word "multicultural" is now used to describe families where at least one parent is not Korean.

Today, the vast majority of "multicultural" children are the offspring of the tens of thousands of Southeast Asian and Chinese women who come to South Korea as marriage migrants. With the help of matchmaking agencies that operate overseas, they often marry local men who are not viewed as desirable husbands by Korean women.

Yun notes that despite official efforts to help economically and socially integrate these families into South Korean society, reducing prejudice towards them remains a challenge.

Children "who have foreign mothers are bullied and are outcasts at their schools," says Jolly Regacho, 43, a volunteer at the Asan Migrant Centre, 86km south of Seoul, where she works with many migrant brides from Indonesia, Vietnam and her native Philippines.

She explains that because of its connotation with migrant women from less developed countries, the word "multicultural" has become synonymous with "poor".

Their children "don't want to be called 'multicultural'", Regacho says. "They want to be treated like a Korean."

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A role model?

Han appears in a YouTube video in which he's approached by a Korean comedian who attempts to strike up a conversation in English. In this apparently staged encounter, the host seems surprised that Han doesn't understand him and he switches to Korean; the implied gag is that this teenager who looks African actually is Korean.

To Gregory "Chan-wook" Diggs-Yang, chairman of the Movement for the Advancement of the Cultural-diversity of Koreans (MACK), this kind of "joke" suggests that many South Koreans still aren't ready to "accept a Korean who doesn't look Korean".

Diggs-Yang, 42, is the son of an African American father and Korean mother and spoke with Al Jazeera from Seattle, Washington.

He points out that other black Koreans like the singer Insooni and NFL MVP Hines Ward achieved acclaim in South Korea, but didn't change overall attitudes towards mixed-race people.

Diggs-Yang sees Han's success, however, as an indication of greater social openness towards mixed-race Koreans.

For a black Korean to make it in the fashion industry is a sign that "things are going in the right direction", he says.

"To be considered beautiful is really great for a mixed Korean," Diggs-Yang says.

Han says he hopes that his success can somehow inspire other biracial Koreans, although he notes that he "hasn't accomplished enough yet to be considered a role model".

But Han doesn't want to be known as "multicultural" - he thinks it carries with it a notion of "pity".

"I prefer to be called 'mixed blood'," he says. "I'm not ashamed about it."