Chō-Senjiryakketsu

The Chō-Senjiryakketsu (超占事略決) is an ancient book written by Asakura Hao during his first life.

About
The Chō-Senjiryakketsu was written by Asakura Hao during his first life. Every secret of his Onmyōdō techniques was included within the book's 16 chapters, ranging from soul manipulation and methods for making Shikigami to fortune telling techniques and battle strategies. It is oriented towards advanced shaman studies and is very hard to read.

After Hao was defeated by the Asakura family, the book was sealed away in the shrine built for him in the Mountains of Kimon. The Asakuras also sealed his two Shikigami Zenki and Goki within the book; upon their release, they will try to kill anyone present to protect their master's secrets.

After learning that Hao was participating in the Shaman Fights in the year 2000 Asakura Yohmei tasked his grandson's fiancée, Kyōyama Anna, to deliver the book to his grandson Asakura Yoh to aid him in defeating Hao once more. Tamamura Tamao, who had followed them, accidentally released Zenki and Goki, though Anna quickly defeated and resealed them into her 1080 Prayer Beads after learning so from the book. The defeat of the Shikigami somehow caused damage to Hao, who knew it was related to his two former Shikigami.

After Anna brought it America and learned its secrets, she gave it to Silva, claiming she did not need it anymore as she had learned everything from it.

Anna's knowledge of the Chō-Senjiryakketsu was later used to train Yoh and his teammates Umemiya Ryunosuke and Johann George Faust VIII.

Spells

 * Gōma Chōbuku (降魔調伏): Anna uses this technique with her string of 1080 pearls to gain control over Asakura Hao's shikigami, Zenki and Goki.
 * Chō Senji Ryakketsu - Fumon Tonkō (超占事略決 - 巫門遁甲 Ultra Senji Ryakketsu - Shamanic Oracle): Using this spell enables one to read the flow of furyoku and determine its course. Effective use can render most furyoku attacks ineffective.
 * Chō Senji Ryakketsu - Fumon Goryoue (Ultra Senji Ryakketsu - Shamanic Soul Pacification): A powerful exorcist magic employed by Matamune that allows him to form his O.S. Oni Goroshi in combination with the Fumon Tonkou technique. The technique creates an Oversoul in the shape of an enormous katana, which has the power to cut through the most powerful spirits. However, it exhausts a great deal of furyoku in the process. The technique later inspires Yoh and Amidamaru's Spirit of Sword oversoul.
 * Chō Senji Ryakketsu - Mikazuki no Harae (超占事略決 - 三日月ノ祓 Ultra Senji Ryakketsu - Crescent Moon Purification): This was a secret exorcist magic left to Yoh by Matamune, to help vanquish the Oni that Anna created. However this technique depleted the reserve furyoku within Matamune, and as a result, sent him to the hereafter.
 * Chō Senji Ryakketsu - Jugon Zonshi (Ultra Senji Ryakketsu - Healing Spell): A Taoist healing spell combined with a mantra, it keeps chi from leaving the body to restore health. The spell is mastered by Faust VIII, allowing him to heal and resurrect others using his Eliza Operieren Oversoul technique.
 * Chō Senji Ryakketsu - Kinji Jusatsu (Ultra Senji Ryakketsu - Forbidden Killing Curse): A killing curse that has the ability to strip the soul from the body for an instant kill. However, Kanna Bismarch's attempt to use it on Tamurazaki Midori is ineffective; he reveals it is because the spell only works on those who believe in the afterlife, which Tamurazaki does not. Furthermore, the spell leaves the body intact, allowing the person to be resurrected.

Anime/Manga Difference
In the anime, instead of learning from the book by reading it, the users literally experience the book by being drawn into it; inside is a whole different world where they are able to converse with Onmyōji Asakura Hao.

Trivia

 * The Chō-Senjiryakketsu appears to be based on the Senji Ryakketsu (占事略决, lit. The Summary to Judgements of Divinations), a text attributed to the legendary onmyouji priest Abe no Seimei during the Heian Period in Japan. The text contains 6000 forecasting and 36 fortune-telling techniques based on divination using shikigami, though most of the divinations were for fairly mundune purposes like determining the gender of a child, finding missing objects, and advice for daily life.