Behind K-pop's rapid growth and immense popularity, there is a persistent, chronic problem that follows fame: Stalkers, often called "sasaeng" in Korea.

"I am not sasaeng. I am just a genuine fan who really loves NCT," said an 18-year-old girl who wished to remain anonymous.

She claims that all her actions are out of sincere support and love -- taking taxis to follow her favorite singer as he goes about his day and waiting for hours at the airport to take photos of the group, to name but a few. She admits that she even knows where the celebrities live. "Sometimes I spend about 300,000 won ($217) on taxis to follow NCT's schedule. They even talk to me in person sometimes!"

That "talk" involved members telling her to go home now.

Call for end to harassment

Despite the growing awareness of the need to respect artists' privacy, the excessive actions of some individuals continue to torment celebrities who call for relief from constant harassment by "sasaeng."

“Sasaeng” is a term used to describe fans who invade artists’ privacy, often exhibiting aggressive and obsessive behaviors.

After months of harassment by sasaeng, Renjun of NCT said on the fan communication platform on April 11, "Sasaengs are nothing but scary stalkers to me. They follow me, sit next to me on planes, and take photos of me while I sleep. It's a huge burden for me," Later that month, Renjun announced he would take a break from work citing health reasons.

He continued to be hounded by phone calls from sasaeng and, in June, he took action by posting what he thought was a phone number of sasaeng on a fan communication platform. It turned out that the number belonged to a non-fan. When the incident caused an uproar, Renjun posted an apology on social media.

Haechan, another member of NCT, has also suffered from sasaeng harassment. In November last year, a sasaeng walked into Haechan’s home, where he lives with his family.

The methods used by sasaeng to reach celebrities have become increasingly cunning. Some make calls by manipulating phone numbers and pretending to be fellow K-pop group members. Techniques commonly used in voice phishing scams are now being employed by sasaeng. Some even call during live broadcasts to verify if the number they have is the celebrity's.

Some sasaeng use K-pop stars' frequent international travels as additional opportunities to follow them. “On a return flight to Seoul after a fan signing event, we found that someone had already pre-booked and changed the in-flight meals for the members' seats,” said TXT’s Taehyun through the fan communication platform Weverse on June 29, adding suspicion that it might have been the act of sasaeng.

Asked about the allegations that sasaeng fans had changed in-flight meal orders, a Korean Air official said, “To change in-flight meal reservation information, one would need the ticket reservation number and the phone number associated with the reservation record. Whether it was a sasaeng's work needs to be confirmed."

The official, however, did confirm that actions by sasaeng fans have caused inconvenience on multiple occasions.

“Sasaeng fans have repeatedly bought tickets just to follow stars into the area past the immigration only to cancel the tickets right before the flight, demanding refunds. We have had to implement cancellation fees. These fees are not solely due to sasaeng issues, but they have certainly been a factor,” the official said.

An Asiana Airlines official also said the company instituted penalty rules for ticket cancellations made just before boarding due to troubles with sasaeng.

Some stars have resorted to drastic measures to avoid sasaeng harassment when traveling.

During a Naver V Live broadcast in 2019, BTS’s V also revealed that BTS uses private flights due to sasaeng issues.

"We would like to fly on regular flights, but some people figure out our flight schedule and sit next to us. It's very uncomfortable because we can't relax in our private space. It scares me a lot and I wish it would stop," he said.

The problem of saesaeng harassment persists despite entertainment agencies' efforts -- ranging from warnings to legal actions -- to protect their artists.

Edam Entertainment, singer IU's agency, claiming severe privacy violations at airport security zones, duty-free shops, aboard flights and at hotels, issued a press statement on June 18, which said, "Please refrain from attempting conversations, taking photos, giving gifts, or filming the artist onboard."

K-pop powerhouse, SM Entertainment, announced on March 6 that it would take legal action on sasaeng harassment of NCT members. But warning appears to have had little impact given the continued harassment experienced by Renjun.

Hybe, which established a task force in 2023 to tackle the illegal trading of stars' flight information, recently reported that they had identified social media accounts trading artists' flight information. They have secured evidence to identify these individuals and submitted it to the police.

The police, for their part, are reported to have conducted long-term investigations both domestically and internationally and some cases have been sent to the Seoul Central District Prosecutors' Office. The illegally traded information was used to obtain seat information to board the same flight and attempt close contact with the celebrities.

Flocks of fans following idol members are a common occurrence but dangerous situations often dp arise. On June 16, fans who gathered at Incheon International Airport to see the boy group Riize returning from an overseas event broke an automatic door when things became disorderly.

Photos taken in such situations often become commodities. Fans who cannot attend events sometimes hire others to get photos or purchase photos. Posts selling photos taken at airports or other events are easy to find on social media platform X.

Photos of stars are not the only thing for sale on the Internet.

It is not difficult to find posts offering to sell information about K-pop singers, including their homes, personalities, phone numbers, relationship status and even details like their exes.

"I can't exactly count the number of purchase requests, but I do make some money out of it," said an anonymous X user who posted about selling celebrities' private information.

"I don't worry about the agency's warning. They don't take serious actions on sasaeng or people who provide information on artists," added the user.

Kwak Keum-joo, a professor of psychology at Seoul National University, explained that obsession with celebrities is often accompanied by fantasies about the object of affection.

“Having affection for someone is natural, but if that affection becomes excessive and especially if the person is not someone you interact with in your daily life, one may create a distorted fantasy about the person and become obsessed with it,” Kwak said.

Kwak further explained that sasaeng fans' actions are a form of self-defense. “Some overly obsessive fans cannot tolerate any deviation from the image they have created in their minds. They continue their excessive behavior to maintain their affection and fantasy.”

Kwak also noted that the diffusion of responsibility in crowd psychology encourages excessive actions among sasaeng fans. “When acting in a group, people become more aggressive and are less likely to recognize the wrongfulness of their actions. They mistakenly believe they have no responsibility for their actions as more people are acting just like them.”

“It is a shame that sasaeng problem continues to persist, but celebrities must maintain their fandom to survive, so this issue is likely to persist,” Professor Kwak added.