The Hoki-Naiden is a treatise on divination that was handed down to subsequent generations as a text compiled by ABE no Seimei. In fact, it was created after the death of Seimei (there are various theories as to when it came into existence).
Its formal name is 'Sangokusoden Onmyokankatsu Hokinaiden Kinu-Gyokuto Shu' but this is sometimes abbreviated to 'Kinu-Gyokuto Shu'.
A Kinu, a sacred bird that symbolizes the sun, is a golden bird with three legs that is said to be an inhabitant or an incarnation of the sun. A Gyokuto, a rabbit that symbolizes the moon, is said to be an inhabitant of the moon. These symbols indicate that this book contains the secrets of the Onmyoji (practitioners of Onmyodo, the Way of Yin and Yang), who are said to have understood the circulation of ki (energy) and been able to divine the future by observing the movements of the sun and the moon.
In later years, a more readable version called 'Hokisho' was published. For reference, 'Hoki' means saiki (ritual utensil) in ancient China. According to the tradition, it is said that this book was written by Monju Bosatsu (Manjusri) in Tenjiku (India), and was later handed down to Hakudo shonin, who was Seimei's legendary master, before it was passed down to Seimei. (According to another view, it was handed down to ABE no Nakamaro, but due to his death in Tang before returning home, it was brought to Japan by KIBI no Makibi, and passed down to Seimei, who was considered to be a descendant of Nakamaro.
In the beginning of the book, there appears an anecdote which shows how important the book was.
Priest Doma (Doman ASHIYA) living in Harima Province was defeated by Seimei in a magic competition in front of the Emperor and became his pupil thereafter. However, he was watching for a chance to bring down Seimei. One day, he knew that a secret book (Kinu-Gyokuto shu) was in the possession of Seimei. So, Doma had an adulterous relationship with Seimei's wife, 梨子, and tried to pump her for information on the whereabouts of the book. Seizing the opportunity when the relationship with Seimei's wife became closer, Doma extracted the information from her that the secret book was in a stone box. However, she said even she did not know how to open the box.
He had her show him the box while Seimei was away and somehow managed to open it.
Then, when Seimei returned home, Doma said to him, 'The secret book of divination now belongs to me.'
Seimei reproached Doma, saying, 'The book is the hard-earned result of my practice of asceticism in Tang.
There's no way you own it.'
Doma thought, 'This is the best opportunity to kill Seimei.' and said to him, 'Then, if I really have the secret book, I'll cut your head off.' and Seimei carelessly agreed. Then, Doma showed him Kinu-Gyokuto shu, which he had transcribed beforehand, and decapitated Seimei.
Around the same time, Hakudo shonin, who had passed down Kinu-Gyokuto shu to Seimei, came to Japan being aware that Seimei had been killed. Around the same time, Hakudo shonin, who had passed down Kinu-Gyokuto shu to Seimei, came to Japan being aware that Seimei had been killed. After that, in order to avenge the murder of his disciple, together with resurgent Seimei, he headed for Doma and 梨子, who had not only betrayed Seimei but also become Doma's wife.
Is Seimei here?', Hakudo asked Doma.
Doma replied, 'He once lived here but was killed by cutting off his head.'
Then, Hakudo said, 'That cannot be true.
I just met him.'
Doma replied, 'It's what you say that cannot be true.
If Seimei were still alive, you could cut off my head.'
So, Hakudo called Seimei, who had just risen from the dead, to appear before Doma. Thus, Doma was decapitated according to his promise and 梨子 was also killed.
In this way, suggesting that anyone who reads this book recklessly or superficially deserves to die, this anecdote represents that this book should be given the highest secrecy. In addition, placing this story at the beginning of the book makes the book seem even more mysterious and holy.
The book consists of five volumes.
The first volume describes engi (writing about the history) of Gozu Tenno (deity said to be the Indian god Gavagriva) and various Hoi-jin (deities of bearings) and their fortunes.
The second volume explains engi of the world's first deity, Bango-o, and its children, and also describes fortunes on calendar.
The third volume explains nacchin and kubo (both are the techniques of divination), etc., which are not described in the first and the second volumes.
The fourth volume expounds on the theory of fortune regarding feng shui and architecture.
The fifth volume expounds on lunar mansion fortune-telling, which is a part of esoteric astrology.
The fourth and fifth volumes obviously have different natures compared to those of the first through the third volumes. The first and second volumes were written first, and after which the third volume was added as an enlarged edition of the previous volumes. It is thought that the fourth and fifth volumes, which are considered to be independently-created, were incorporated into those volumes.