A bronze mirror with an inscription indicating it was made in 235 in China during the Wei Dynasty has been on display at the Tokyo National Museum since Friday.
The mirror, which has been in the care of an art collector in the Kanto region for about 20 years, is believed to have been made from the same template as two similar mirrors found in the Otaminami tomb in Kyoto and the Amamiyayama tomb in Osaka.
The museum and the National Research Institute for Cultural Properties in Tokyo have been investigating the mirror since the end of last year. While it is not known where the mirror was originally found, some experts said it may be one of 100 bronze mirrors given to Japan by the Wei Dynasty when Queen Himiko of the legendary Yamatai Kingdom sent her first delegation to China in 239, four years after the mirror was believed made.
The mirror is 17.3 cm in diameter and depicts four deities, including the Red Bird of Summer and the White Tiger. Around the edge of the mirror are 39 characters comprising the name of its maker and a prayer for prosperity.
While other Wei mirrors have surfaced in Japan bearing the dynasty inscription, experts remain divided over whether they are among the 100 given to Himiko or were actually made in Japan.
Shinya Fukunaga, associate professor at Osaka University, said he believes the mirror on display at the museum was imported from the Korean Peninsula or China, but is not one of Himiko's 100 mirrors.