Babies were crying as their mothers limbered up for something unusual at Tokyo's Yoyogi National Stadium in November. There was good reason for the unease: Five thousand people were in the audience.
Over 70 women in red T-shirts cautiously pushed their babies in strollers to the center of the floor, and as if on cue the children fell silent.
Music began playing, and expressions of nervousness on the mothers' faces instantly became broad smiles. They pushed and swung the strollers, shook their bodies, and bounced and twirled around. Their babies gazed in curiosity at the movement.