Egyptian mummies were made by embalmers after death, but in Japan some Buddhist monks prepared their own bodies for preservation while still alive. This episode explains sokushinbutsu, the practice in which ascetics pushed austerity so far that their bodies mummified naturally, with no preservatives applied afterward. It grew out of Shugendo, a mountain religion taking shape around the seventh century that blended Vajrayana Buddhism, Shinto, and Taoism, and drew on the Shingon school founded by Kukai, who is said to have stopped eating and drinking and died chanting on Mount Koya. The goal, the episode explains, was to become a bodhisattva who remains to help others, not an escape from life.

In the Dewa Mountains of northern Japan, a preparation of about 3,000 days centered on mokujiki, tree eating: no grains or cooked food, only pine needles, seeds, nuts, and tree resin. Water was then restricted, and the monk died in deep meditation chanting the nembutsu. The Meiji government banned the practice in 1877, but a monk the episode calls Bukai completed it in secret in 1903, and researchers from Tohoku University exhumed his remains in 1961.

• How giving up fat and eating antimicrobial resin starved and poisoned the bacteria that drive decay
• Why Japan’s humid climate made the diet essential, compared with the frozen, dry Spiti Valley that preserved Sangha Tenzin
• The live burial with a bamboo breathing tube and bell, a story 20th century research found little evidence for
• Honmyokai, preserved at Honmyoji temple in Yamagata Prefecture and still venerated
• Ueda Akinari’s 18th century tale of a self-mummified monk dug up and revived, and the game Sekiro