Chugaisho is a collection of narrative recordings during the times under cloistered rule. It is also classified as a setsuwa (collection of anecdotes) or diary. NAKAHARA no Moromoto, Daigeki (senior secretary), transcribed the discourse of FUJIWARA no Tadazane (1078-1162), Kanpaku (chief adviser to the emperor) of Chisoku-in Temple. The title was named by combing the last name of Moromoto 'NAKAHARA' and his office 'Geki' (secretary). In two volumes.
The first volume contains articles from 1137 to August 1148, and the second volume, articles from August 1148 to 1154. Every article details the date and place. This is why Chugaisho is sometimes viewed as the selection of Tadazane's discourse from Moromoto's diary.
It is written in a blend of kanji, katakana, and hiragana. As well as "Fukego," a quotation collection from Tadazane's discourse, Chugaisho is precious because it conveys the real lives of aristocracy at the time including yusoku-kojitsu (knowledge of court rules, ceremony, decorum and records of the past) as well as official court events.
It is included in the volume which is entitled "Godansho Chugaisho Fukego" of 'Nihon koten bungaku taikei' (Japanese Classic Literature Systematic Edition) (the publisher is Iwanami Shoten).