It should have happened by now. Optimists in South Korea had expected K-Pop to invade the US even before Psy went supernova in November 2012 with Gangnam Style. But tours by the likes of the Wonder Girls, sold out shows in New York by Girls Generation and a Will.i.am collaboration with 2NE1 have all as yet failed to place K-Pop at the top of the charts – or in the popular consciousness of the American public. But now Crayon Pop, a five-piece girl group only formed in 2012 by Chrome Entertainment have achieved quite a coup. Late last week Lady Gaga announced via Twitter that the quintet will open her summer concerts in North America.