^^I think she probably put it back on? Didn't she get rid of the yukata during the performance in the carts? At least she did in the fancams of Osaka.
It makes me sad, though that those fancams are mostly of JYJ fans. You only see them even when the others are singing.
^
It's not a single.
From the stream it sounds like JYJ are performing now. But that could also be music that they have playing in the background, I'm not sure.