Very muted, but it sounds like she's singing to me.
I swear, a lot of you are going conspiracy-theorist on Ayu for no real reason whatsoever. It's rather sad that people always think of "playback/lipsynching" when she sounds okay. Gone are the days when people just enjoyed a concert without thinking: "Oh, maybe she isn't really singing this..". It's a sad day in the world of an Ayu fan.