Kamaitachi

What is a kamaitachi?

Kamaitachi (鎌鼬) is usually translated "sickle weasel." It names an invisible attacker that rides the wind and cuts people. Strangely, the name was used both for the creature and for what it did. Japanese dictionaries define kamaitachi first as a phenomenon: the skin suddenly splits open in a wound that looks as if it were made by a sharp sickle. Only after that do they explain that people once blamed an unseen weasel. The Heibonsha World Encyclopedia describes the kamaitachi as a demon that rides in on a whirlwind to cut people, or even to drink their blood. Its wounds look like sickle cuts, yet they are said to cause neither pain nor bleeding.

The kamaitachi is found all over Japan, but it is most at home in the snow country. Dictionaries count it among the "seven wonders of Echigo," the old province that is now Niigata Prefecture. It is also an old seasonal word in Japanese poetry. The Nihon Kokugo Daijiten lists it as a winter word in haikai, with an example from 1695 about a wound on the shin.

What the wounds were like

The records are surprisingly consistent. A 1916 note from Ito District in Wakayama, held in Nichibunken's Kaii/Yōkai Densho Database, says that the kamaitachi lives inside whirlwinds and cuts the legs of anyone it meets. The wound is deep and large, but it hardly hurts. The Niigata Prefectural History calls it a cut shaped like a sickle blade, with surprisingly little blood or pain for its depth. A 1955 account from Ina in Nagano describes the kamaitachi as a kind of weasel so fast that it slashes the shins of passers-by and is gone before anyone can see it. People were most often cut when they fell over.

Edo-period writers knew the same picture. The physicist Terada Torahiko quotes the 1666 story collection Otogibōko, which says the phenomenon was common in the Kantō region. A whirlwind strikes a traveller roughly, and his thigh splits lengthwise as if cut with a razor. There is little pain and no blood. The book adds, in a detail that says a lot about its time, that samurai of proper family were never harmed, while commoners were struck even if they were rich.

Weasels, gods and swords

How a weasel came to be blamed is not clear. The Heibonsha encyclopedia states plainly that it is unknown why whirlwinds and weasels were linked. The folk explanations vary a great deal from place to place:

• Three gods working together. In the Nyūkawa area of Hida (Gifu Prefecture), the kamaitachi was said to be three gods travelling together. The first knocks a person down, the second cuts with a blade, and the third puts medicine on the wound. That would explain why the cut does not bleed or hurt. In many modern retellings the three gods have become three weasels, and this "weasel trio" is probably the most familiar version today.
• An angry god's sword. In Shibata in Niigata, some said a god was playing with a drawn sword and a person had wandered into its path. A record from Ibi in Gifu explains the name as kamae-tachi, "a sword held at the ready." In Shimōsa and Kai, an Edo essay says, the wind god himself carried a sword (see Fūjin).
• A smith's lost secret. A 1916 story from Shinshiro in Aichi says the kamaitachi was once the secret art of a swordsmith, who passed it to his apprentice but died without teaching him how to seal it away. It has been loose ever since.
• Sickles and mantises. In Shikoku, it was said to be the ghost of a sickle left in a graveyard or out in the open. In Katakai, now part of Ojiya in Niigata, people told of a giant mantis on Kamakiri-zaka, "Mantis Slope," that cut anyone who fell there. Some dialects even call the mantis kamaitachi.

Certain places were known to be dangerous. People in Niigata said that anyone who fell at Kurosaka, between Mount Yahiko and Mount Kugami, would surely be cut.

Regional names and cures

The wind had different names in different regions. According to the Niigata Prefectural History, it was called kamakaze, "sickle wind," in Sagami (Kanagawa) and akuzenshikaze in Shizuoka. One essay records the name ichimokuren in Ise, Mino and Suruga, and kamakaze again in Sagami. Terada quotes the Unpyō zasshi, which says that in the western provinces there is something called kazekama, "wind sickle." In Gunma a deadly gust that attacked horses, the daiba, was also sometimes called kamaitachi.

Because the cuts were blamed on an evil spirit, the cures were magical. The most widespread was to burn an old calendar to ash and put it on the wound, or to drink it in hot water. In Shibata, a burnt Ise calendar was thought to work best. People there also believed that treating a calendar carelessly could bring the kamaitachi down on you, and in the Shin'etsu region stepping on a calendar was said to do the same. Another Edo writer suggested putting marten fur on the wound. An Edo medical essay reports that on Sado, stitching a kamaitachi wound or putting a plaster on it was thought to kill the patient. The advice was to wash it with a boiled sweet-flag root, or simply leave it alone, since it would heal in a few days.

Toriyama Sekien's whirlwind weasel

The kamaitachi got its lasting image from the artist Toriyama Sekien, whose Gazu hyakki yagyō (1776) was the first of his four illustrated catalogues of yokai. His picture, which the National Diet Library has digitized, shows a small furry animal with a long, curved, blade-like claw, spinning at the centre of a great spiral of wind full of torn leaves. He gave it the Chinese name kyūki (窮奇), a monster from Chinese myth, written with the reading kamaitachi beside it. Later artists and, eventually, games and anime took over this sickle-clawed weasel in a whirlwind.

Modern explanations

People have long tried to explain the cuts scientifically. Japanese dictionaries record the theory that a whirlwind creates a pocket of vacuum, and that skin which touches it splits as the air inside the body rushes out. The Britannica Japan entry lists several competing explanations: dust devils, the vacuum theory, a cold-weather theory, an electrical theory, and sudden changes in air pressure.

The vacuum theory has never had much support from physicists. In his 1929 essay Bakemono no shinka ("The Evolution of Monsters"), Terada Torahiko recalled a meteorologist's claim that the low pressure inside a whirlwind splits the skin. He found it hard to believe, since a leg is not a rubber ball that bursts. His own view was that fragments of wood, bamboo or grains of sand, driven by the very high winds inside a whirlwind, strike the skin and slice it. He added that a scientific explanation does not make the mystery smaller, because the real investigation only starts there.

No single explanation has been proven. Many of the folk accounts mention a fall just before the cut, and the snow-country setting fits the cold-weather theory, but the records cannot settle the question. Meanwhile the old name has survived for wounds that seem to appear from nowhere.