Tradition / Region: Chinese Mythology, Japanese Mythology
Alternative names: Kettetsu, Gnawing Iron
Category: Cow
The Myth
Kettetsu is a strange beast from the southern regions, described with the horns and feet of a water buffalo and a body covered in jet-black fur. Its name means gnawing or eating iron.
The creature feeds on iron and drinks water. According to ancient accounts, its feces were harder than ordinary metal and could be used by people to make sharp weapons.
Descriptions of Kettetsu appear in the Shenyi Jing and later Chinese works such as the Bencao Gangmu. Japanese encyclopedias, including the Wakan Sansai Zue, also recorded the creature from these earlier accounts.
Some traditions placed Kettetsu among a group of iron-eating beasts associated with the baku. The baku itself was sometimes described as a creature capable of eating copper and iron, and in some accounts the two creatures were identified with one another.
In later interpretations, the legend of iron-eating beasts may have developed from ancient descriptions of pandas. An animal originally described as eating bamboo may have been misunderstood as eating the arrows and other objects made from bamboo, copper, and iron, eventually producing the strange tradition of a beast that consumed iron.
Sources
Takahashi, Toshihiro. “囓鉄 (Kettetsu).” 新版TYZ 妖怪図鑑 (New TYZ Yokai Encyclopedia). June 27, 2021. Accessed August 16, 2026. https://tyz-yokai.blog.jp/archives/1078437874.html