Yata no Kagami

The Yata no Kagami (八咫鏡 meaning "Eight 咫 Mirror" - 咫 being a unit of measurement) is a sacred mirror in Shintoism and one of the Three Imperial Sacred Treasures that was used in the enthronement ceremonies of a new Japanese emperor. It represents wisdom (and in some translations, honesty), and is known for its ability to reveal the truth or true nature of whatever is reflected.

Owners of Note

 * Ame-no-Uzume - set up the mirror as part of a plan to lure out Amaterasu
 * Amaterasu - kept the mirror after leaving the cave
 * Ninigi - was gifted the mirror by his grandmother Amaterasu

Origin
After a fierce argument with her brother Susano-o, Amaterasu hid inside the Ama-no-Iwato ("heavenly rock cave"), which hid the light and warmth of the sun from the world. Although many dieties tried to lure her out with many different methods, all failed until Ame-no-Uzume made an attempt. Placing a mirror in front of the cave which had been forged by the diety of mirrors, Ishikori-dome, she began her plan. Dressing herself in flowers, she started dancing on top of an overturned tub in front of the cave. The other gods began to laugh, even more so when she shed her "clothing" and danced naked. Curious to know what the fuss was about, Amaterasu looked out of the cave, and saw her own reflection in a mirror Uzume had placed in her view. She left the cave, and the other gods quickly blocked the entrance, persuading her to stay. Amaterasu accepted and returned to the heavens, bringing the sun with her.

The mirror that was used during this mythological event is said to be the Yata no Kagami, which Amaterasu kept until it was given to her grandson Ninigi-no-Mikoto when he was sent to pacify Japan.

Modern Counterpart
The Yata no Kagami is said to still be held within a chamber in the Ise Shrine that worships Amaterasu. As one of the Three Sacred Treasures, it is considered to precious to show and so it is not known what it looks like, and some even consider it the most precious of the three artifacts.

There was a fire in the chamber that held the mirror in 1040, which may have resulted in the loss of the original mirror, but this is unconfirmed as the mirror has never been revealed.