the online database of Japanese folkore



Translation: weasel
Alternate names: often referred to as ten, the Japanese marten
Habitat: found all across Japan, particularly in mountainous areas
Diet: carnivorous; feeds on small wild animals

Appearance: Like birds and spiders, many other animals develop into yōkai when they reach a certain age. Japanese weasels, known as itachi, are disconcerting animals. They bring ill omens, and people fear their particular brand of magic. Like most animals-turned-yōkai, they possess shape-shifting abilities in addition to a number of supernatural powers.

Interactions: Itachi are tricksters and pranksters, but generally shy away from interaction with humans. As a result, they are mistrusted and disliked. Itachi calls are also considered to be ill omens. After the yelping cries of a group of itachi are heard, misfortune and despair always follows. Though itachi can transform, they prefer to use other kinds of magic—usually with unfortunate results for their targets. When an itachi is seen standing on its hind legs it is said to be bewitching a human—perhaps hypnotizing them into leaving out food or performing some other task for the weasel’s benefit. Itachi are dangerous in groups. They gather together at night, climb up onto each other’s shoulders, and create huge columns of fire which erupt into whirlwinds. These are frequently blamed for starting conflagrations which can burn down entire towns.

Origin: In the old days, weasels were believed to transform into ten (martens) or mujina (badgers or tanuki, depending on the region) after reaching an old age. Additionally, the names ten and itachi were often used interchangeably. As a result, there is confusion over which animal is being referred to in many stories.

Other forms: Itachi are often considered to be the most skilled shape-changing animals, possessing more forms than any other shape-changer. An old phrase about animal yōkai goes, “Kitsune nanabake, tanuki hachibake, ten kubake”—foxes seven forms, tanuki eight forms, martens (i.e. itachi) nine forms. When an itachi changes its shape, it usually adopts the form of a young priest boy dressed in clothes that are too big for him. This form is used chiefly to acquire alcohol, which the weasels cannot brew. Itachi also frequently adopt the forms of other yōkai in order to scare humans. One of their favorites is the ōnyūdō: a colossal, bald-headed giant who terrorizes villages, destroys houses, devours livestock and even eats people.

Alphabetical list of yōkai