Early Ryukyu Burial Customs

From Maritime Ryukyu, 1050–1650, by Gregory Smits (University of Hawaii Press, 2018), Kindle pp. 50-51:

The practice of placing corpses in baskets or cages and leaving them at the top of trees or poles to decompose was characteristic of the Northern Tier Cultural Zone and regions farther north. Within the Ryukyu islands, the practice has been documented in Amami-Ōshima and in parts of central and northern Okinawa. Nagoya Sagenta was a Satsuma retainer. After residing in Amami-Ōshima between 1850 and 1855, he wrote a detailed description of the local culture, Nantō zatsuwa (Tales from the southern islands). It explains that, after the death of a priestess, “her corpse is placed in a large box, which is suspended from atop a tree for three years. Then the bones are washed and placed in a jar.”

Similar practices have been documented in places along the coastline of the Japan Sea in Akita, Yamagata, and Ishikawa Prefectures. In those places the remains are hoisted aloft after cremation. In Korea, hoisting (non-cremated) bodies into trees was done in the case of deaths from smallpox and other diseases. The practice was both a de facto sanitary measure and was thought to mollify the angry deity who had caused the disease by offering up the body. A broad range of northern Asian peoples, from the Koryaks in Kamchatka west to Mongolia, traditionally disposed of corpses or bones by placing them on platforms or in trees. Bones of humans or hunted animals thus offered up toward the heavens were believed to be reborn.

There is only one known example from Fukuoka, but folklore from the region such as the legend of the “bone-hanging tree” attests to the former existence of the practice. Kashiigū, a shrine in Fukuoka City with ties to Korea, derives its name from the legend that Emperor Chūai’s coffin was hung in a shii [as in shiitake] tree (Castanopsis cuspidata, Japanese chinquapin).