Rokudai Shōjiki
Rokudai Shōjiki (六代勝事記) was a Japanese history book written in the early Kamakura period, narrating events at that time in the order they occurred. The Rokudai, which literally means six generations, refers to Emperors Takakura, Antoku, Go-Toba, Tsuchimikado, Juntoku and Go-Horikawa. The fact that Go-Horikawa is referred to as The Reigning Emperor (今上天皇) suggests that the book was written shortly after the Jōkyū War (1221). For a long time, Minamoto no Mitsuyuki had been considered as the author of the book. Recently, however, historians have argued that Fujiwara no Tadataka, who was retired at the time the book was written, is more likely the actual author.
The book contends that Emperor Go-Toba lost the Jōkyū War because of his immorality, that he was basically a villain of the whole story, and that the event therefore does not necessarily challenge the authority of the emperor and his court. This viewpoint, which was convenient for both the imperial court and the newly formed Kamakura shogunate, had profound influence in later relations between the people of kuge and that of samurai.
See also Imakagami, which also narrates events in Kamakura period.