Meaning
What does Virgin killer sweater mean?
Virgin killer sweater is the commonly used nickname of turtleneck top that has a missing backside, possibly out of seductive reasons, similarly to the keyhole turtleneck.
It became a popular phenomenon among Japanese Twitter users, as well as otakus in early 2017.
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Origin
What's the origin of Virgin killer sweater?
Half a year prior to the first appearance of the sweater’s term, a similar clothing design was worn by the Japanese cosplayer, Noraneko, who named the top “Sukebe knit” meaning erotic knit.
The nickname, along with the sweater didn’t receive a lot of attention at this time.
The term for the clothing, according to the Pixiv Encyclopedia, originates from a tweet, which lists “clothes that kill virgins”.
Spread & Usage
How did Virgin killer sweater spread?
After the tweet in 2017, users were reposting and sharing the photos from the woman’s top.
Several hundred illustrations were created and uploaded to Nico Nico Seiga as well as Pixiv and eventually even Tumblr.
The phenomenon had grown to such an extent, that even people from outside the otaku community had taken notice of the trend.
Japanese news sites were publishing articles about the sweater.
The Kano sisters, Mika and Kyoko, who are Japanese celebrities, also rode the publicity wave, which was created by this design.

External resources
- Know Your Meme – Virgin-Killing Sweater