History and Provenance

The treasures are first described in the Kojiki (712) and the Nihon Shoki (720), Japan's oldest chronicles. In the myth of the heavenly cave, the other gods forge the mirror Yata no Kagami and string the jewels Yasakani no Magatama to draw the hidden sun goddess Amaterasu back into the world; the sword Kusanagi no Tsurugi is found by the storm god Susanoo in the tail of the eight-headed serpent Yamata no Orochi and presented to his sister. Amaterasu grants the three to her grandson Ninigi as he descends to rule the land, and they pass to Jimmu, the legendary first emperor, as the insignia of sovereignty.

Over time the objects came to rest in different places. The mirror is enshrined at the Ise Grand Shrine, the chief shrine of Amaterasu; the sword is kept at Atsuta Shrine in Nagoya; and a jewel, with replica mirror and sword, is held in the sanctuary of the Tokyo Imperial Palace. The historical record is tangled by loss: several medieval accounts say the original Kusanagi went down with the child emperor Antoku at the Battle of Dan-no-ura in 1185, and that a replacement was made, while other accounts say the object lost was already a copy. Replicas of the sword and mirror are documented from the 9th century. At each modern accession, 1989, 1990 and 2019, the regalia have featured in the rites while remaining wholly hidden from view.