The following information is excerpted from Brent Swancer’s “The mysterious little people of Japan“:
“The Ainu knew these creatures as the Koropokkuru, also often written in other ways such as Kor-pok-un-kur, Koro-pok-guru, and Koro Pokunguru. They are also sometimes referred to as the Tsuchigumo. The name Koropokkuru is most commonly translated as “the people who live under the burdock leaves,” and implies the diminutive size of the creatures. In some stories a whole family was said to be able to fit underneath one burdock leaf, with one such leaf measuring about 4 feet across. The size reported for the Koropokkuru, however, actually varies from tradition to tradition, and they were said to be anywhere from 2 or 3 feet in height all the way down to only mere inches in height.
In addition to their small size, the Koropokkuru were said to be rather rough and primitive looking, with large heads, prominent brows, and short, squashed noses. They were sometimes said to have reddish skinned faces. Most commonly Koropokkuru are described as being rather hairy and odiferous. The non-Ainu Japanese of the time, and even early western explorers, already regarded the indigenous Ainu people as hairy brutes, and those who were acquainted with the Koropokkuru as well described these creatures as even more so.
Despite this brutish appearance, the Koropokkuru had some signs of sophistication. They were said to use flint or stone knives, scrapers, and other simple implements, and were also known for their ability in the art of pottery, which the Aiunu were not known to practice. Also unlike the Ainu, the Korropokkuru were said to dwell in pit dwellings, basically huts built over round holes in the earth, and this led them to sometimes be referred to as “the pit dwellers.”
The Koropokkuru were also known to be capable of speech, and were able to communicate with the Ainu in this manner.
According to Ainu lore, this dwarf race was exceedingly shy and did not like to be seen. Nevertheless, they were known to trade with the Ainu on occasion, although such transactions were brief and typically done under the cover of night.”