Sokushinbutsu refers to an ancient Buddhist practice in Japan where its practitioners would reach a form of further enlightenment through self-mummification.
The practice of self-mummification started over a thousand years ago by a priest named Kuukai at a temple complex on Mount Koya.
The monks would go through an extreme process of starvation, eating only nuts and seeds for one thousand days while also taking part in exhaustive physical activity.
For the next thousand days they would eat only bark, roots and drink a poisonous tea made from the sap of the Urushi tree. This caused vomiting, a loss of bodily fluids, and it would preserve the body by killing off maggots.
In the last stage, the monk would lock himself in a stone tomb, where he would sit in the lotus position. His only connection to the outside world was an air tube and a bell. Each day he rang the bell to let those outside know he was still alive.
When the bell stopped ringing, the tomb would be sealed for another thousand days. Eight year after the process began the tomb would be opened to see if mummification was successful.
It is believed that many hundreds of monks tried, but when the tombs were opened the bodies were found rotted.
If the mummification had been successful, they were immediately seen as a Buddha and put in the temple for viewing. Only 24 successful mummifications have been discovered to date.
Despite having their eyes removed, the monks are believe to be able to see into the souls of the living.
The Japanese government outlawed the practice in the 19th century, but it has continued into the 20th.
The most famous of these monks is Shinnyokai Shonin of the Dainichi-Boo Temple on the holy Mount Yudono. You can go visit him, and let him see into your soul yourself.