Final answer:
The sun goddess Amaterasu gave three sacred treasures to Ninigi-no-Mikoto as signs of dominion: the mirror Yata no Kagami, the jewel Yasakani no Magatama, and the sword Kusanagi no Tsurugi. These items are central to the Imperial Regalia of Japan and signify wisdom, benevolence, and valor, which are the virtues expected of a ruler. They are deeply ingrained in Shinto lore and the historical legitimacy of the Japanese Emperor.
Step-by-step explanation:
The sun goddess Amaterasu bestowed upon her grandson, Ninigi-no-Mikoto, three sacred treasures as signs of dominion when she sent him to rule the Earth. These treasures are now known as the Imperial Regalia of Japan and consist of the mirror, Yata no Kagami, which signifies wisdom; the jewel, Yasakani no Magatama, representing benevolence; and the sword, Kusanagi no Tsurugi, embodying valor. These items play a crucial role in the enthronement ceremonies of the Japanese Emperor and are deeply rooted in the Shinto religion.
Amaterasu, being the Sun Goddess, has been regarded as the ancestress of the Imperial line according to the mythology integrated into Japanese statecraft. The objects have been revered throughout Japan's history, and their symbolism extends to the virtues that the ruler is expected to exhibit. The importance of these treasures is not just due to their divine origin but also due to their role in legitimizing the divine right of emperors to rule Japan.
The mirror, often considered to have power in reflection and truth, became a symbol of authority in the court and was associated with the Queen Mother of the West's cult in Han times. This cultural reverence for mirrors easily translated into the mythology of Amaterasu, who used the mirror to be lured out of a cave, thereby bringing sunlight back to the world. Thus, when combined with the sword and the jewel, these regalia represented the strength, compassion, and wisdom required to rule.