Rokudai Shojiki (war tales concerning six emperors) (六代勝事記)
"Rokudai Shojiki" (or "Rokudai Shoshiki") is a historic tale written in chronological form in the early Kamakura Period of Japan.
"Rokudai" refers to six emperors of Takakura, Antoku, Gotoba, Tsuchimikado, Juntoku, and Gohorikawa (togin [the emperor reigning at that time]) but does not include the dethroned Emperor Kujo (Emperor Chukyo). As Emperor Gohorikawa was referred to as togin, it is considered that "Rokudai Shojiki" was written immediately after the Jokyu War. It used to be said that the author was MINAMOTO no Mitsuyuki, but recently FUJIWARA no Takatada, the former Sadaijin (minister of the left), who retired and became a priest, is considered to be the most likely author.
The military of Kamakura bakufu (Japanese feudal government headed by a shogun) defeated the Imperial forces in the Jokyu War and the retired Emperor Gotoba and his followers were exiled, and such unprecedented events shook the authority of the Imperial Court and the Shinkoku-shiso (the thought of Japan as the land of the gods) at the time "Rokudai Shojiki" was written. This book was among the first to argue that the Imperial forces were defeated in the war because the retired Emperor Gotoba was an "evil king" who lacked virtue, so the defeat didn't mean repudiation of emperors or Japan as the land of the gods. The book was also harsh on the retired Emperor Juntoku who lost his decedents' right of succession to the Imperial Throne by siding with the retired Emperor Gotoba, referring to him as "Dethroned Emperor of Sado" and discriminated in favor of Emperor Awanoin (the retired Emperor Tsuchimikado) who didn't willingly come into the war. This perspective was useful in hiding the decline of the authority of the Imperial Court and at the same time benefited the Kamakura bakufu to alleviate the criticism that they were an enemy of the court, resulting in the influence on the historical view of the following generations.
One theory states that the author defended Emperor Gohorikawa, who was helped to the throne by the Kamakura bakufu, and his father, Gotakakurain (Imperial Prince Morisada), who was placed in the cloister government without being Emperor. Another theory points out that the author was aware of the readers of "Imakagami" (The Mirror of the Present) because "Rokudai Shojiki" started with the enthronement of Emperor Takakura where "Imakagami" concluded, although the two books were not explicitly related.