“A monk who chose to perform self-mummification, or sokushinbutsu, began by abstaining from grains and cereals, eating only fruits and nuts for one thousand days. He spent this nearly three years meditating and continuing to perform service to the temple and community. Then for the next thousand days the monk ate only pine needles and bark. By the end of the two thousand days of fasting, the monk’s body had wasted away through starvation and dehydration. While this satisfied the requirement for suffering, it also started the process of mummification by removing excess fat and water, which would otherwise attract bacteria and insects after death. Some of the monks drank tea made from the bark of the urushi tree during their fast. Also known as the Japanese Varnish Tree, its sap is normally used to make a lacquer varnish, and it contains the same abrasive chemical that makes poison ivy so unpleasant. Urushi is so toxic that even its vapor can cause a rash, and it remains in the body after death. Drinking urushi tea served to hasten the monk towards death as well as make his body even less hospitable to insects.
Finally, the monk would enter a cramped, specially built tomb and sit in meditation as his acolytes sealed him in, leaving a small tube to allow air to enter. He spent his last days in sitting in meditation, ringing a bell occasionally to signal to those outside that he was still alive. When the bell stopped, the acolytes removed the breathing tube and sealed the tomb completely. After a thousand days, his followers opened the tomb and examined the body. If there was no sign of decay, the monk had achieved sokushinbutsu and was placed in a temple and worshipped as a Living Buddha. If not, he was reburied with great honor for the attempt.”