There are social clubs in this country for everything from Gospel Singing (try to imagine a bunch of Japanese singing and dancing like black gospel choirs) to Ballroom Dancing.  But times are changing; young people don't have the money that they used to have to spend on these clubs to keep them entertained.  Instead they are turning to the street.  Walk around any city in Japan and you will come across young people learning to dance in front of any part of a building that shows a reflection. 

Judging from their ability, I think these two girls were getting some daytime practice before they hit the more crowded and competitive night scene.