Scattered throughout Northern Japan around the Yamagata Prefecture are two dozen mummified Japanese monks known as Sokushinbutsu, who caused their own deaths in a way that resulted in their mummification. The practice was first pioneered by a priest named Kuukai over 1000 years ago at the temple complex of Mount Koya, in Wakayama prefecture. Kuukai was founder of the Shingon sect of Buddhism, which is the sect that came up with the idea of enlightenment through physical punishment. A successful mummification took upwards of ten years. It is believed that many hundreds of monks tried, but only between 16 and 24 such mummifications have been discovered to date.
The elaborate process started with 1,000 days of eating a special diet consisting only of nuts and seeds, while taking part in a regimen of rigorous physical activity that stripped them of their body fat. They then ate only bark and roots for another thousand days and began drinking a poisonous tea made from the sap of the Urushi tree, normally used to lacquer bowls.