K-pop has traditionally thrived on idol worship from the hundreds of thousands of young groupies who spend lavishly on concert passes, air tickets and merchandise.
It is these fans who propel performers from relative obscurity to almost instant super-stardom, the fans who will buy the products the stars are paid to endorse, the fans who will fill up venues with their ecstatic screams.
And K-pop stars know this — "fan meets" are held on a regular basis, managers keep in contact with fan clubs to make sure stars stay on the radar, and every concert or appearance is inevitably punctuated with "thank yous" and "I love yous" from the idols to their supporters.
"We are nothing without our fans," is probably the most common phrase heard from K-pop stars.
But what if some of these fans started sending letters written in menstrual blood to their boyband idols? Or began installing hidden cameras in their idols' homes and cars, stalking them so aggressively that car accidents resulted?
What if a fan decided she loved her idol group so much that she would "destroy" his rivals by doping another boyband's drink with poision?
All these horror stories are true and they are committed by a new breed of K-pop groupies gone wild — "Sasaeng", or "private" fans, whose quest to worship their idols have taken on horrifically disturbing proportions in the past year.
What started out as groups of teenaged girls banding together to support their K-pop idols has morphed into an ugly new phenomenon involving physical violence, blatant intrusions into personal privacy, and even sexual favours offered in exchange for information about the stars.
Who are they?
Sasaeng are usually female, starting as young as 13 to about 22, and they have made it their life's goal to make sure they are noticed by their idols, by hook or by crook.
Top K-wave stars targeted include male groups and stars like JYJ, TVXQ, B2ST, Jang Geun Suk, Big Bang, Super Junior, SHINee and SS501′s Kim Hyun Joong.
Korean managers speaking to Korean media have revealed that popular stars have between 500 to 1,000 sasaeng fans. On any given day, the stars have at least 100 full-time stalkers on their heels.
JYJ and TVXQ, in particular, have been the target of obsession. Here's a list of what they have had to go through in the past year:
-- TVXQ's phone lines are tapped and personal conversations recorded
-- Several sasaeng saved their menstrual blood and had it delivered to the JYJ members.
-- TVXQ's apartment was broken into and sasaeng attempted to kiss them while they were sleeping
-- JYJ's Yoochun had sasaeng fans who installed spy cameras in his parking lot and took pictures of him.
-- TVXQ's Yunho was poisoned by an anti-fan who gave him a drink with an adhesive mixed in. He had to have his stomach pumped.
These examples are just a few of the ways sasaeng fans terrorise their K-wave idols.
These sasaengs' extreme behaviour extend to every aspect of their lives. They do not return home but instead usually sleep at PC Bang (Internet cafes) after a full day of stalking. Many skip school and some drop out completely.
Their lives become filled with every move their idols make. The sasaeng position themselves strategically around the homes or the management companies of their idols and communicate via Kakao-talk, the Korean version of Whatsapp, boasting about photos they are able to snap or reactions they are able to provoke from the stars.
"We check each others' blogs out and look at their pictures and blog entries. The more exclusives there are, the more views you get, so there's a lot of competition," a 16-year-old sasaeng posted on popular Korean forum soompi.com.
Competition is so rife that there have been reports of sasaengs attacking fans within their groups because they were unhappy that other fans were able to speak or touch their idols.
An ex-idol manager told Korean news entertainment site Newsen that stars have woken up and opened their doors in the morning to find urine and faeces on the floor.
"It's as if they are marking their territory," he said.
He admitted that he has had to hit a sasaeng for the security of his charges.
"After the schedules are finished, hundreds of fans swarm in. One member even used to get pulled around by the hair. I had no choice but to use violence," he said, adding that even the use of insecticide spray does not deter them.
"Fans actually feel proud of it. I've seen some say 'I was hit by our oppa's manager.' Sasaeng fans think that violence and verbal assaults are a way of getting closer to their favourite idol," he told Newsen.
Rumours on the forum abound about some sasaeng prostituting themselves to support their daily stalking — an expensive affair, as many of the sasaeng, unable to drive, hire special taxi drivers to follow their idols.
According to Korean newspaper JoongAng Daily, there are taxi services catering specifically for these fans. They are willing to speed at up to 200 km/h, chasing after the company vans transporting the stars.
One driver, Kim, 37, told JoongAng Daily that he charged $30USD an hour.
"I charge $30 USD per hour. It's hard to stop because you can make a lot of money out of it. I take sasaengs about two days out of the week," Kim is reported as saying.
Other drivers charge an average of $500 USD for nine hours of ferrying.
These taxis can be found waiting outside celebrity dorms or broadcast halls near Cheongdamdong, Seoul, to pick up desperate sasaeng.
And if all of this wasn't already disturbing enough, there are actual companies that fans can hire to spy on their oppas (or big brother, as they affectionately refer to their idols) 24/7.
According to Korean online news site OhMyNews, the lucrative sasaeng industry has prompted the opening of companies specialising in helping sasaeng stalk their stars when they are physically unable to.
"Sasaeng fans are stalkers. They're not normal, they've mentioned killing someone, and even themselves. Some even ask us to find out what color clothes their idols wear to bed," revealed one such company employee.
According to him, one sasaeng even offered to fork out $100,000 USD if the company could steal her idol's underwear.
Idols fight back
As the abuse by sasaeng fans escalates, K-pop stars have also been fighting back in ways ranging from ranting on Twitter accounts and blogs, agreeing to meet them in the hopes that they will leave, and most drastically, literally hitting them back when attacked.
The video below shows JYJ's Yoo Chun, 26, allegedly grabbing and tossing a sasaeng's hand aside after she attempted to slap his face to provoke a reaction.
Another JYJ member, Jaejoong, was recorded using expletives against a female fan (see below) and physically assaulting her.
"Following me around and contacting me... it's really fun for you guys... never really thinking about how much stressful it is for us. I'd rather become normal and live without any of this," Jaejoong is heard ranting in between slaps.
Jaejoong, 26, is also heard describing how some sasaeng make taxi drivers beat red lights or drive in reverse, endangering pedestrians and other drivers.
His rants can be heard in the video below -
The clips elicited as much public sympathy as anger, and Jaejoong eventually apologised on his Twitter account.
An ex-idol manager interviewed by Newsen said that while "there's no excuse for the use of violence, I can understand what he (Jaejoong) must have been thinking... once this accumulates, there's only so much a human being can take before it all explodes."
Other harassed stars have taken their anger online. Super Junior's Hee Chul, 29, deleted his Twitter account in July this year.
"Don't come in front of the house or the borough office... I don't think I can do this. I still have trauma from my car accident and it is scary, driving away like my life depends on it. I can't help it because I only have one life," he tweeted.
Actor Jang Geun Suk also took to Twitter, furious that sasaeng had bugged his car with a GPS system and were using it to stalk him via taxi.
"Sasaeng fans, you guys think you've figured out my every move by following me around. But do you know this? Those actions push me further away from you. So smile when you can because when I'm mad it can get ugly," Jang threatened.
Calls for authorities to step in and do something about the situation are intensifying now that the sasaeng are starting to endanger the public with their rash traffic-rule flouting and violent behaviour.
Prominent talk show hosts have spoken out to condemn the sasaeng, saying that it's only a matter of time before lives are lost as a result of their stalking.
In part 2 on our series on "Sasaeng Stalkers", Yahoo! Singapore speaks to a Singaporean fan who encountered the sasaeng herself on a trip to Seoul last year, and hear from experts on K-pop culture about whether the phenomenon will slowly but surely become a regional one.