Shoku Nihon Koki (Later Chronicle of Japan, Continued) (続日本後紀)

Shoku Nihon Koki is a history compiled in 869 during the Heian period in Japan, and is the fourth of the Six National Histories (Rikkokushi). It covers the 18 years of the reign of Emperor Ninmyo, from 833 to 850. The compilation was begun in 855 on the Imperial order of Emperor Montoku, and completed in 869. It is one of the main historical sources for the period of the shift from direct rule by the emperor to the regency, and describes the emperor's deeds. It consists of 20 volumes in annalistic style.

The compilation of this book was begun in 855 by FUJIWARA no Yoshifusa, TOMO no Yoshio, HARUZUMI no Yoshitada and Toyomichi YASUNO. Yoshifusa's brother FUJIWARA no Yoshimi later joined the compilation effort but passed away before the work was completed, Yoshio was exiled due to the Otenmon incident (an event centering around the destruction of the main gate of the Imperial Palace in Kyoto), and Toyomichi was appointed as the Vice-governor of Shimosa. However, because no one else was provided to help, only FUJIWARA no Yoshifusa and HARUZUMI no Yoshitada remained as compilers in the end. Therefore, it is said that their views are strongly reflected in the text, Yoshifusa's in editorial policy, and Yoshitada's in description.

It is the first work among the Rikkokushi to cover only one emperor's reign. The Jowa Incident is also described in this book.
The 'Shoku' in the title of this fourth book Shoku Nihon Koki means 'continued,' so it can be seen as a direct continuation of the third book Nihon Koki (Later Chronicle of Japan), but in contrast to that third book, which covers the reigns of four emperors, and the second book Shoku Nihongi (Chronicle of Japan, Continued) which covers the reign of nine, this fourth book covers only one, Emperor Ninmyo
As the reign of Emperor Ninmyo was in a time of peace after the reigns of Emperor Saga and Emperor Junna, and as nothing big occurred except the Jowa Incident, this book is said to have more detailed descriptions of court ceremonies, etc., but less material related to politics. According to one theory, it was written to emphasize the legitimacy of Prince Tsunesada's demotion from Crown Prince and the raising of Prince Michiyasu(Emperor Montoku) as the new Crown Prince in 'the Jowa Incident'. In the points of emphasizing the emperor's actions and reflecting the authentic style of the National Histories, it greatly influenced later works such as Nihon Sandai Jitsuroku (Veritable Records of Three Reigns of Japan). It is said that abridged manuscripts were circulating in the late Heian period, and that the oldest of these (from the Hoen era) was supplemented by using text from Ruiju Kokushi (Classified National History). Furthermore, as the complete text was not available when the Six National Histories were transcribed by the Sanjonishi family, and commentaries and other writings were sometimes incorporated into the text which had pages out of order due to binding errors, many mistakes and omissions were made that are still present in the current printed editions.