well you probably noticed Ayu isn't using a hand-mic for this song, cause of all the choreography, hand moves.
When artists use these mikes they're most likely lipsync-ing, almost all major artists do this..
but of course they don't all do this all of the time.. but when they do they most likely use a pre-recorded vocal track specially for the live performances..
or they use it for tv broadcasts and dvd's.. all like teddbear55 said
