Wakan Sansai Zue
In Japan, during the Edo period, it was also believed that there were also kakuen in Japan, and in the encyclopedia Wakan Sansai Zue from the same period, it was explained under the name "yamako" (玃), and in this entry, bringing up the yōkai "kuronbō" (黒ん坊) that lived deep in the mountains of Hida and Mino (now Gifu Prefecture), it stated "quite conceivably, this is probably a type of yamako." A kuronbō is a black large monkey-like creature with long hair and walks like a human. They are able to understand human language and able to read human's minds, so even if people attempt to kill a kuronbō, the kuronbō would quickly flee, so it is said that they are definitely unable to be captured.