The three objects representing three signs of dominion which were given by Sun Goddess Amaterasu to her grandson, Ninigi-no-Mikoto while sending him as the ruler of Earth were:
1. The Jewel,the sign of benevolence.
2. A Mirror, the symbol of purity.
3. Kasunagi, the grass-mowing sword representing the courage.
The mythology is recorded in Nihon Shoki, the Chronicle of Japan which tell us history of Japan from earlier times up to 720 AD. It is said the Sun Goddess sent Ninigi to earth or Japan to bring peace and plant rice. Ninigi has been considered as the great-grandfather of Emperor Jimmu- the first emperor and founder of Imperial power of Japan.