What is Ippon-datara?
Ippon-datara is a mountain yokai said to have only one eye and one leg. It is told of in the Hatenashi Mountains along the border of Nara and Wakayama Prefectures, on Mount Obagamine in Nara, and in the mountains of Kumano in Wakayama. Almost no one has seen it. It is usually described through what it leaves behind: on the morning after a snowfall, a trail of huge single footprints about 30 cm wide dotting the mountainside.
It appears on “Hate no Hatsuka”
In the Hatenashi Mountains, Ippon-datara was said to appear only on December 20. This day was called “Hate no Hatsuka” (the twentieth of the final month) and treated as an unlucky day on which people were warned not to go into the mountains. One theory even says the name Hatenashi (“no passage”) comes from the way no one would walk the paths on that day.
On Mount Obagamine, too, December 20 was a day when no one should enter the mountain. There is a legend there of a demon god called Izasa-ō, who was sealed away by a high priest but allowed to roam freely once a year, on December 20. Ippon-datara is said to be either Izasa-ō himself or one of his forms.
How it is described
Descriptions vary from place to place. In the Hatenashi Mountains it is said to have one huge eye like a plate. On Obagamine it is described as looking like a utility pole with eyes and a nose, leaving one-legged tracks as it somersaults across the snow. Some stories say it does no harm to people, while others say that meeting it means death.
Tatara ironmaking and Ippon-datara
One theory says the word “datara” is related to tatara, the old Japanese method of ironmaking, and to the smiths who worked its bellows. In tatara ironmaking, workers pumped huge bellows with one foot for long hours to blow air into the furnace and stared into the fire with one eye to judge its temperature. Many craftsmen were said to end up with a weakened leg and failing sight in one eye. The one-eyed, one-legged figure of Ippon-datara may reflect these smiths, or Ame-no-Mahitotsu, a one-eyed god of smithing, who came to be told of as a yokai. It has also been pointed out that Ippon-datara is often said to appear near old mines.
One-legged mountain gods
In many parts of Japan there are traditions that the god of the mountain has only one leg. Customs are also handed down of offering a single sandal to the mountain god, or dedicating one giant straw sandal. Folklorists think one-legged yokai such as Ippon-datara may be the beliefs in such mountain gods, retold over time as frightening monsters. China, too, has legends of a one-legged mountain creature called the shanxiao, and some theories link it to Ippon-datara. In Tono, Iwate Prefecture, there is also a tale of a one-eyed, one-legged monster slain by a hunter.
One-legged yokai around Japan
Stories of yokai that leave one-legged tracks in the snow are found all over Japan, under names such as Yuki-nyūdō and Yuki-baba. Other well-known one-eyed or one-legged yokai include Hitotsume-kozō and the hopping umbrella Karakasa-kozō. The Kumano mountains are also rich in legends of mountain gods and spirits such as tengu and Yamauba.
