Entered the seminary at Churenji (Yamagata prefecture) when he was 18 years old. Practiced asceticm at Mount Yudono. As per his will, priests enshrined his body in an underground chamber to be exhumed and mummified in three years. Since exhumation was illegal in Japan at that time, his body remained there until excavation.
Bukkai practiced self-mummification known as sokushinbutsu, consuming a strict diet that would preserve his body in death. The mummification process was not completed after his death due to exhumation becoming illegal.
Researchers petitioned the Japanese government for permission and exhumed the body in 1961.
He died as a result of self-mummification, which he believed would allow him to attain nyūjō, a level of enlightenment that transcended death.
Most sources state that his remains are located at Kanzeon-ji Temple in Murakami City, Niigata Prefecture, however, since there is no such temple in Niigata Prefecture, and there is a reference indicating his remains are at the Kannon-ji Temple, which is in Murakami City, Niigata Prefecture, the reference to Kanzeon-ji Temple is most likely a highly repeated mistake.
Cockburn, T., Cockburn, E., & Reyman, T. (Eds.). (1998). Mummies, Disease and Ancient Cultures. Cambridge: Cambridge University Press. doi:10.1017/CBO9781139878340
Quigley, Christine (1998). Modern mummies : the preservation of the human body in the twentieth century. McFarland, Jefferson, N.C. ; London