The Iwasaki Edition of Nihon Shoki (Nihongi), Volumes 22 and 24

Nihon shoki (Chronicles of Japan, also called Nihongi) is Japan’s oldest imperially sanctioned official history, compiled in the Nara period. It records the history of the country in chronological order from its mythological origins through the reign of Empress Jitō (645–702), recounting myths, legends, and documentary records that
were passed down within the imperial court. Written entirely in Chinese characters, Nihon shoki was recorded in a total of thirty scrolls.
These two scrolls most recently came from the Iwasaki Bunko section of the Tōyō Bunko library, owned by the Iwasaki family, which ran the Mitsubishi conglomerate. Volume 22, “Empress Suiko[554–628],” records incidents related to Prince Shōtoku such as the Twelve Level Cap and Rank System and the adoption of the Seventeen-article Constitution. Volume 24, “Empress Kōgyoku[594–661],” relates the rise of the father-and-son pair Soga no Emishi and Iruka and their subsequent deaths during the Isshi Incident (645). From the diacritical marks and the writing style, this manuscript has been dated to the Heian period, the tenth century.
Both scrolls contain a variety of diacritical marks and notations written next to the texts. Phonetic kana characters and wokototen marks indicating how to read the Chinese characters in Japanese and markers indicating tone—all of which date to the mid-Heian period—are notated in vermillion. In the late Heian period, kana pronunciations and other diacritical marks were added in black ink. These are the oldest diacritics and readings found in any copy of Nihon shoki. In addition, the esteemed scholar Ichijō Kaneyoshi (1402–1481) went over the entire manuscript twice during the Muromachi period, adding his own diacritical marks. Thus this work is considered to be one of the most important existing references for the historical
use of diacritics in the Japanese language.