Taira no Munemori and the Taira clan take the young Emperor Antoku and the three sacred treasures and flee to western Japan to escape pursuit by the Minamoto clan.

Taira no Munemori was heir to Taira no Kiyomori, and one of the Taira clan's chief commanders in the Genpei War.

The Taira was one of the four most important clans that dominated Japanese politics during the Heian period of Japanese history – the others being the Minamoto, the Fujiwara, and the Tachibana. The clan is divided into four major groups, named after the emperors they descended from: Kanmu Heishi, Ninmyō Heishi, Montoku Heishi, and Kōkō Heishi, the most influential of which was the Kanmu Heishi line.

Emperor Antoku was the 81st emperor of Japan, according to the traditional order of succession. His reign spanned the years from 1180 through 1185. His death marked the end of the Heian period and the beginning of the Kamakura period.

The Three Sacred Treasures are the imperial regalia of Japan and consist of the sword Kusanagi no Tsurugi (草薙劍), the mirror Yata no Kagami (八咫鏡), and the jewel Yasakani no Magatama (八尺瓊勾玉). They represent the three primary virtues: valour, wisdom, and benevolence. The actual historical status of these legendary treasures is unknown as they are intentionally kept from public view to symbolize authority.

Minamoto was a noble surname bestowed by the Emperors of Japan upon members of the imperial family who were excluded from the line of succession and demoted into the ranks of the nobility since 814. Several noble lines were bestowed the surname, the most notable of which was the Seiwa Genji, whose descendants established the Kamakura and Ashikaga shogunates following the Heian era. The Minamoto was one of the four great clans that dominated Japanese politics during the Heian period in Japanese history—the other three were the Fujiwara, the Taira, and the Tachibana.