From Wikipedia:
 
Ame-no-Uzume-no-mikoto (, ) is the goddess of dawn, mirth and revelry in the Shinto religion of Japan, and the wife of fellow-god Sarutahiko kami. She famously relates to the tale of the missing sun deity, Amaterasu Omikami. Her name can also be pronounced as Ama-no-Uzume.
 
Amaterasu’s brother, the storm god Susano’o, had vandalized her rice fields, threw a flayed horse at her loom, and brutally killed one of her maidens due to a quarrel between them. In turn, Amaterasu became furious with him and retreated into the Heavenly Rock Cave, Amano-Iwato. The world, without the illumination of the sun, became dark and the gods could not lure Amaterasu out of her hiding place.
 
The clever Uzume overturned a tub near the cave entrance and began a dance on it, tearing off her clothing in front of the other deities. They considered this so comical that they laughed heartily at the sight. This dance is said to have founded the Japanese ritual dance, Kagura.
 
Amaterasu heard them, and peered out to see what all the fuss was about. When she opened the cave, she saw her glorious reflection in a mirror which Uzume had placed on a tree, and slowly emerged from her hiding spot.