Who performed at the 2012 olympic opening ceremonies?

This person named Hatsune Miku idk who that is but she is at 21%.

It's actually only a possibility that she will be singing, and she is a Vocaloid. A Vocaloid is an electronic voice based off of a real singers voice, that is given a personality and an image. Hatsune Miku is one of the most popular and one of the oldest Vocaloids. If she does sing she will represented with a hologram, like at the live Vocaloid concerts.