Cavern
This cave serves as a mausoleum to Tanzei Shonin (1552–1613), a Buddhist ascetic who is interred in a stone structure within. The opening is large enough for an average-sized person to enter and leads to a larger cavern beyond.
Tanzei instructed his disciples to excavate a cave in the mountainside behind the temple, and then construct a stone mausoleum within. In 1613, at the age of 62, he entered the cave to pray and fast. At his request, his disciples closed him in, leaving just a few air holes. Three days later, when they could no longer hear Tanzei chanting sutras, they sealed the tomb completely.
The practice of Buddhist priests enduring harsh conditions to the death while praying for the salvation of all is known as sokushinbutsu, or becoming a Buddha within one’s own body. Tanzei believed that his actions would ensure the salvation of all those who would later come to worship at his tomb.
There were plans during the Meiji era (1868–1912) to place Tanzei’s remains in a grave. However, when the chamber was opened, the remains were found to be perfectly mummified, so it was decided to inter the body in a new mausoleum instead. This new tomb, a cube of stone measuring approximately 1.5 square meters, remains in the cave for people to visit and pray.