http://en.wikipedia.org/wiki/Tachikawa-ryu
There's lots to read there, but The Skull Ritual from 1270 really takes the cake:
QUOTE
If anyone would practice this secret Dharma (Ritual) and attain great Siddhi (magical powers), he must construct an object of worship (honzon). I do not refer to the auspicious face of a woman here; this Misogi (purification Rite) is a skull. There are, in fact, ten different types of skull that may be used:
1 the skull of a wise man
2 the skull of an ascetic
3 the skull of a king
4 the skull a shogun
5 the skull of a great minister
6 the skull of an elder
7 the skull of a father
8 the skull of a mother
9 a “Thousand Cranium” skull
10 a “Dharmadhātu” (entire material universal) skull.
The first eight are clear enough. The “Thousand Cranium” skull is made by grinding the tops of a thousand men’s skulls into flour and molding the bone-paste into a honzon. For the “Dharmadhātu” skull, one must go to a cemetery on the chōyō (an onmyodo festival held on the 9th day of the 9th month. Since the number 9 is the perfect maximum yang/yō in Chinese divination it is seen as a particularly powerful and auspicious day. See: kuji-in), collects a large number of skulls, chants Dākini represent an especially crucial component of the Skull Ritual) incantations/prayers, and prays over the skulls. Finally, he takes the one, that when placed at the bottom of pile of skulls repeatedly rises to the top of the pile; or else he goes out on a frosty morning and selects the one that on which no frost has formed. Or, best of all, he selects a skull that is completely free of suture lines.
Whatever type he chooses can be made into a Honzon (本尊) (object of worship). For any of the ten types of skull there are three methods of construction possible. These are “the whole head”, “the small head”, and “the moon-shaped head”. For “the whole head”, the officiant uses the original skull. To this he adds a chin, puts in a tongue and teeth, and covers the bone with a hard lacquer so that it looks just like the unblemished flesh of a living person. When the skull has been completely formed, he places it in a box. Then he must have sexual intercourse with the skull and with a beautiful and willing woman, and must repeatedly wipe the liquid product (the mixture of male and female seminal and vaginal secretions) of this act on the skull until it reaches 120 layers. Each night at midnight he must burn “Spirit returning” incense (frankincense/hangon-kō), pass the smoke through the eye holes of the skull, and chant a “spirit returning” mantra fully and perfectly one thousand times.
After carrying out the procedure above for a number of days, the officiant places the appropriate charms and secret talismans (sōō motsu) into the skull. Once this procedure has been meticulously completed, he covers the skull with three layers of gold and silver leaf. Over these layers, the mandala must be inscribed, and then more gold and silver leafe applied, then another mandala applied over that, just as before. Thus the layers of gold and silver foil and sacred writings are built up – the outer layers are five and six, then in the center thirteen layers, all over the base of 120 layers of the red and white elixir (male and female sexual secretions). (Presumably this will equal the thickness of muscle and flesh of a real person) The ink of the mandlas should also be the twin fluids of intercourse.
Cinnabar (mercury sulfide) is rubbed into the tongue and lips, the teeth are set in silver leaf, and the eyes are painted in comely fashion, or, precious gems (jade, mother of pearl, or cornelian) can be used for the eyes. Them face is painted white and rouge patted in to create the appearance of a beautiful woman or boy. The image must look prosperous and have a face that smiles without the slightest hint of reproach.
During the entire process the sacred skull is to be kept on an altar in a place where no one ever goes, and various delicacies, beautiful flowers, and fine wines are to be offered to it. No one must go there (to the skull altar) but the craftsman, the adept, and the woman. There (at the skull altar) they must happily and willingly and ceaselessly disport themselves as if celebrating the first three days of the New Year. Each act and word must be wholly free of any sign of care.
Once the Honzon is finished, it is installed on the altar. Offerings of rare things are made daily; spirit-returning incense is burned; and the various observations are carried out at the hours of the Rat, the Ox, and the Tiger (midnight to dawn). With the arrival of the Hour of the Hare (dawn), the Honzon is placed in a bag made of seven layers of brocade. Once this bag has been closed, it is not easy to reopen. Every night the bag is held close to the adept’s body to keep it (the skull) warm; during the day it is placed on the altar, where delicacies (fowl, fish, meats, blood, rice, and so on) must be gathered and offered for its nourishment.
For seven years, day and night, the adept must and will devote the whole of his being and mind to this practice. When the eight year comes, the ascetic will obtain siddhi (magical powers). For those who reach the highest grade of practice, the Honzon will return to life and speak aloud (presumably predicting the future and bestowing upon the practitioner great wisdom and knowledge). Since it will inform him of all events of the universe, he should listen carefully to it and thus become as someone with divine powers. For practitioners of the middle rank, the Honzon will tell them the meaning of their dreams. It will not speak to those of the lower ranks, but all their desires will come to be realized in accordance with their wishes.
The second method, the “Small Head” method, exists because of the difficulty of carrying around a whole head. The top of one whole skull can be divided into eight pieces and each piece used as a face lacquered into a plate made of wood of a sacred tree. Again, one sketches in the mandala in thin layers, daubs the Honzon with the twin waters of intercourse, inserts the appropriate charms and talismans, and decorates the face just as before. The “Small head” is then hung around the neck but under the garments, and nourished just as before.
In the case of the third. “Moon-Shaped” method, a whole cranium is cut off at the eyebrows, the brain pan is carefully dried and cleaned, and the moon-shaped inner cavity coated with the lacquer of the twin waters of intercourse. Various charms and talismans are placed in it, again the mandala is laid out in thin color, all as before. On the surface of the “Moon-skull” the practitioner must paint a Honzon while continuously reciting mantras. Cinnabar in packed inside. Then the practitioner is to wrap the skull in a nine-layered monk’s habit made from silk stained with menstrual blood of a beautiful young virgin woman. He then places it in a nine-layered casket wrapped in seven layers of brocaded silk, hangs it from his neck under his garments (to keep it dry and warm), and devoutly recites mantras to it wherever he goes.
There are recommended variations on this procedure, from taking the skull to its final installation and resurrection, since several oral (Kuden) teachings have been handed down by the old and wise. I have noted and summarized only about one-hundredth of the whole Ritual. But in general this is how the practitioner carries out this Ritual.[3]
1 the skull of a wise man
2 the skull of an ascetic
3 the skull of a king
4 the skull a shogun
5 the skull of a great minister
6 the skull of an elder
7 the skull of a father
8 the skull of a mother
9 a “Thousand Cranium” skull
10 a “Dharmadhātu” (entire material universal) skull.
The first eight are clear enough. The “Thousand Cranium” skull is made by grinding the tops of a thousand men’s skulls into flour and molding the bone-paste into a honzon. For the “Dharmadhātu” skull, one must go to a cemetery on the chōyō (an onmyodo festival held on the 9th day of the 9th month. Since the number 9 is the perfect maximum yang/yō in Chinese divination it is seen as a particularly powerful and auspicious day. See: kuji-in), collects a large number of skulls, chants Dākini represent an especially crucial component of the Skull Ritual) incantations/prayers, and prays over the skulls. Finally, he takes the one, that when placed at the bottom of pile of skulls repeatedly rises to the top of the pile; or else he goes out on a frosty morning and selects the one that on which no frost has formed. Or, best of all, he selects a skull that is completely free of suture lines.
Whatever type he chooses can be made into a Honzon (本尊) (object of worship). For any of the ten types of skull there are three methods of construction possible. These are “the whole head”, “the small head”, and “the moon-shaped head”. For “the whole head”, the officiant uses the original skull. To this he adds a chin, puts in a tongue and teeth, and covers the bone with a hard lacquer so that it looks just like the unblemished flesh of a living person. When the skull has been completely formed, he places it in a box. Then he must have sexual intercourse with the skull and with a beautiful and willing woman, and must repeatedly wipe the liquid product (the mixture of male and female seminal and vaginal secretions) of this act on the skull until it reaches 120 layers. Each night at midnight he must burn “Spirit returning” incense (frankincense/hangon-kō), pass the smoke through the eye holes of the skull, and chant a “spirit returning” mantra fully and perfectly one thousand times.
After carrying out the procedure above for a number of days, the officiant places the appropriate charms and secret talismans (sōō motsu) into the skull. Once this procedure has been meticulously completed, he covers the skull with three layers of gold and silver leaf. Over these layers, the mandala must be inscribed, and then more gold and silver leafe applied, then another mandala applied over that, just as before. Thus the layers of gold and silver foil and sacred writings are built up – the outer layers are five and six, then in the center thirteen layers, all over the base of 120 layers of the red and white elixir (male and female sexual secretions). (Presumably this will equal the thickness of muscle and flesh of a real person) The ink of the mandlas should also be the twin fluids of intercourse.
Cinnabar (mercury sulfide) is rubbed into the tongue and lips, the teeth are set in silver leaf, and the eyes are painted in comely fashion, or, precious gems (jade, mother of pearl, or cornelian) can be used for the eyes. Them face is painted white and rouge patted in to create the appearance of a beautiful woman or boy. The image must look prosperous and have a face that smiles without the slightest hint of reproach.
During the entire process the sacred skull is to be kept on an altar in a place where no one ever goes, and various delicacies, beautiful flowers, and fine wines are to be offered to it. No one must go there (to the skull altar) but the craftsman, the adept, and the woman. There (at the skull altar) they must happily and willingly and ceaselessly disport themselves as if celebrating the first three days of the New Year. Each act and word must be wholly free of any sign of care.
Once the Honzon is finished, it is installed on the altar. Offerings of rare things are made daily; spirit-returning incense is burned; and the various observations are carried out at the hours of the Rat, the Ox, and the Tiger (midnight to dawn). With the arrival of the Hour of the Hare (dawn), the Honzon is placed in a bag made of seven layers of brocade. Once this bag has been closed, it is not easy to reopen. Every night the bag is held close to the adept’s body to keep it (the skull) warm; during the day it is placed on the altar, where delicacies (fowl, fish, meats, blood, rice, and so on) must be gathered and offered for its nourishment.
For seven years, day and night, the adept must and will devote the whole of his being and mind to this practice. When the eight year comes, the ascetic will obtain siddhi (magical powers). For those who reach the highest grade of practice, the Honzon will return to life and speak aloud (presumably predicting the future and bestowing upon the practitioner great wisdom and knowledge). Since it will inform him of all events of the universe, he should listen carefully to it and thus become as someone with divine powers. For practitioners of the middle rank, the Honzon will tell them the meaning of their dreams. It will not speak to those of the lower ranks, but all their desires will come to be realized in accordance with their wishes.
The second method, the “Small Head” method, exists because of the difficulty of carrying around a whole head. The top of one whole skull can be divided into eight pieces and each piece used as a face lacquered into a plate made of wood of a sacred tree. Again, one sketches in the mandala in thin layers, daubs the Honzon with the twin waters of intercourse, inserts the appropriate charms and talismans, and decorates the face just as before. The “Small head” is then hung around the neck but under the garments, and nourished just as before.
In the case of the third. “Moon-Shaped” method, a whole cranium is cut off at the eyebrows, the brain pan is carefully dried and cleaned, and the moon-shaped inner cavity coated with the lacquer of the twin waters of intercourse. Various charms and talismans are placed in it, again the mandala is laid out in thin color, all as before. On the surface of the “Moon-skull” the practitioner must paint a Honzon while continuously reciting mantras. Cinnabar in packed inside. Then the practitioner is to wrap the skull in a nine-layered monk’s habit made from silk stained with menstrual blood of a beautiful young virgin woman. He then places it in a nine-layered casket wrapped in seven layers of brocaded silk, hangs it from his neck under his garments (to keep it dry and warm), and devoutly recites mantras to it wherever he goes.
There are recommended variations on this procedure, from taking the skull to its final installation and resurrection, since several oral (Kuden) teachings have been handed down by the old and wise. I have noted and summarized only about one-hundredth of the whole Ritual. But in general this is how the practitioner carries out this Ritual.[3]
No matter how jaded your players are I am sure that if in the context of an RPG you have something like that depicted, you will succeed in weirding them out, especially if instead of just focusing on the ghoulish aspect you really get into the OCD particulars of each part of the ritual.
