A Buddhist monk who had followed the practice known as ‘Sokunshinbutusu’ that was often practiced in the ‘Yamagata’ region of Japan by those who ascribed to the religious sect of Shingon.
According to legend, a monk would slowly starve himself from over three thousand days to ten years. All that they would eat to survive were things that grew on trees, such as pine needles, seeds, berries, nuts, resin and even tree bark. Some monks would even go so far as to eat just stones. This diet would cause the monk to lose all fat in the body and afterwards, would eventually stop drinking which would shrivel their skin.
Then they would entomb themselves into a small burial chamber with a small bell and a tube for breathing. If the bell rang once a day, the monk was alive. But if it did not ring, the tube was removed and the chamber sealed. The monks would often die while meditating and chanting a sutra. Sometime later, the body would be exhumed and if found to be preserved, would be venerated and worshiped.
It is said that hundreds of monks would attempt this over the years, but as of the current year, only twenty eight monks were found to have been successful.
Eventually the practice would be banned in the 19th century. The term Daisōjō was the name for the highest rank of priesthood in Japanese Buddhism.