Babymetal

Their first song, "Doki Doki Morning", was released in April 2011. Later the band shot a music video for the song and in October 2011 released it as a DVD single intended for limited distribution. Having been uploaded to YouTube in the same October, initially the video attracted only some Japanese fans of idols, but in about a month was noticed overseas and confused and shocked people worldwide.

I'd say that sums my reaction up quite well.