The work covers the 95-year period from the beginning of Emperor Mommu's reign in 697 until the 10th year of Emperor Kammu's reign in 791 spanning nine imperial reigns. It was completed in 797 AD.
The text is forty volumes in length. It is primarily written in kanbun, a Japanese form of classical Chinese, as was normal for formal Japanese texts at the time. However, a number of "senmyō" 宣命 or "imperial edicts" contained within the text are written in a script known as "senmyō-gaki", which preserves particles and verb endings phonographically.