Following years of girl groups treading the sexy-cute line, the latest trend in K-pop is to go so all-out sexy that some of their music videos look like three-minute soft-porn movies.
The clip for Marionette by rookie quartet Stellar shows rapper Jeon Yul drinking milk that then trickles down her chin to her cleavage.
Ga-In, of the group Brown Eyed Girls, shocked the industry last month with a song titled Fxxk U and an accompanying video in which the 26-year-old singer-actress suggests she's dating a guy who sexually abuses her.
In the last two months alone, several solo acts and groups have released music videos so steamy that YouTube requires users to verify their age before viewing them.
However, those released by more established acts like Ga-In and former Wonder Girls member Sunmi are seen by K-pop fans as being edgy and classy.
Sunmi's video for new single Full Moon offers subtle erotica in a story about two lust-lorn vampires.
"I think these singers push the boundaries for a good reason... the message of Ga-In's song is good, she wants to show how bad it is to be in an abusive relationship," said Indonesian Adam Harianto, 21, who studies here.
"They are smart enough to know what works and what doesn't, especially in a conservative society."
According to US site Kotaku, South Korean media have been sounding the alarm bells about groups being "too sexy" and broadcasters have forced them to temper their outfits and choreography for TV.
Websites like KpopStarz have weighed in, warning that sexy videos may "work in the short term... (but) careful measures must be taken lest (the groups) end up looking desperate".
Brown Eyed Girls fan Isabel Ng, 19, said she doesn't have a problem with sexiness in K-pop, but some of the new groups have gone "too far".
"I know it's a trend but this is too much," said the polytechnic student.
"Groups like Stellar and AOA need to stand out from all the other groups, but they are giving female groups a bad name."
South Korea-based Chinese-American YouTube personalities Stephen Kao and Josh Hone, who host video series This Week in Kpop, told The New Paper via e-mail that for some of the groups, they cross the "fine line between sexy and cheap".
"We don't buy it because we don't believe they are exuding a natural sexy," said Mr Hone, 25.
"In general, I don't think (the girl groups) are going too far," countered Mr Kao, 27.
"My main issue with what they are doing recently is that they aren't pulling off sexy in a believable way. Many times, they seem like high school girls trying to act more mature and sexy than they really are."
Still, he added, the attention-grabbing antics have obviously worked.
"For as much hate as Stellar is getting, everyone knows their name now," said Mr Kao.
Undergraduate Hazli J, 26, agrees.
"(The Marionette video) is over the top. On a marketing level though, it's genius. But it looks like soft porn to me. All in all, because I'm a dude, I like it."
How XXX are they?
We take a look at where the latest oversexed K-pop music videos fall on our "X-o-meter", with the highest, of course, being XXX.
STELLAR - MARIONETTE
Active since: 2011
Who they are: A quartet previously produced by Eric from K-pop boy band Shinhwa. They're so new to the scene they don't even have an official English Wikipedia page. But the online success of Marionette, which has received over two million hits on YouTube in just one week since its release, should change all that.
What the song is actually about: A girl hurting from her on-again bad boy "dragging" her around like a "sad doll".
What you see in the video: One of the girls is so hung up about her boyfriend, she spills milk on herself, and it just happens to trickle to her cleavage. When she's done with that, she and her friends do stripper-style dance moves.
YouTube hits: 2.1 million (released Feb 11)
GIRL'S DAY - SOMETHING
Active since: 2010
Who they are: Once a cute, colourful quintet, Girl's Day dropped a member along the way - as well as their good-girl image. With Everyday 3, their fourth and latest EP released last month, the fun girls-next-door have been replaced with leather-and-lace-wearing vixens.
What the song is actually about: Girl finds out boy is cheating on her, so she sits at her "sadly crying piano".
What you see in the video: Girl's Day look like they're auditioning for a regular spot at a semi-classy gentleman's club, doing a peek-a-boo dance with their high-slit skirts as well as various unflattering dance moves.
YouTube hits: 3.6 million (released Jan 2)
GA-IN - FXXK U (FEAT. BUMKEY)
Active since: 2006, as part of quartet Brown Eyed Girls
Who she is: You may remember her as the girl in Psy's Gentleman video. Now, this singer-actress is using her status as the "K-pop star with the most rumours" - plastic surgery and celebrity boyfriends - to be one of the most boundary-pushing female K-pop artists right now.
The video for the song was deemed "unfit for broadcast" by major Korean broadcaster SBS.
What the song is actually about: Ga-In alludes to having relationship problems that "scare" her and a guy who won't stop harassing her with his "bad hands".
What you see in the video: Described as the K-pop version of Eminem and Rihanna's Love the Way You Lie, the heartbreaking clip shows Ga-In struggling, in various situations, against a guy who won't let go. Fans have discussed how the song's lyric - "I don't wanna lay down next to you as if it's natural" - and scenes in which Korean actor Joo Ji Hoon forcefully push her against a glass door suggest Ga-In was trying to portray sexual assault. It also includes an artistically-filmed shower scene, where only the outlines of the couple's bodies are seen.
YouTube hits: 2.3 million (released Jan 27)
SUNMI - FULL MOON
Active since: 2007, as part of quintet Wonder Girls
Who she is: Since embarking on her solo career last year, Sunmi has restyled herself as a sex kitten, literally crawling on all fours in the music video for her debut solo single 24 Hours and now getting into vampire-themed erotica with new song and video Full Moon.
What the song is actually about: Hey, it's full moon tonight, baby, so let's get it on!
What you see in the video: Sunmi cleverly adapts the 'full moon' theme into one in which she's a vamp singing and dancing sexily to attract a man. It's fifty shades of seduction, with class.
YouTube hits: 690,000 (released Feb 16)
AOA - MINISKIRT
Active since: 2012
Who they are: AOA - short for Ace of Angels - are an eight-member group with a complicated angel-mortal concept: The seven "angels" dance and play musical instruments; the last is half-angel, half-mortal because she only plays the drums.
What the song is actually about: A long-suffering girlfriend wonders why her boyfriend doesn't notice her even when she "wears a miniskirt that's too short".
What you see in the video: The girls aren't giving up on their clueless boyfriends. They cheekily unzip the sides of their miniskirts to show off sexy stockings, stick their bums out and shake them about, writhe on the floor and eat fruit suggestively, though none of it is particularly titillating.
YouTube hits: 2.8 million (released Jan 15)
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