Kitsunebi

Kitsunebi (狐火) is an atmospheric ghost light told about in legends all across Japan outside Okinawa Prefecture. They are also called "hitobosu," "hitomoshi (火点し)," and "rinka (燐火)."

Kimimori Sarashina, a researcher of local stories, summarizes the features of the kitsunebi as follows: in places where there'd be no presence of fire, mysterious flames like those of paper lantern or a torch would appear in a line and flicker in and out, with fires that have gone out sometimes even appearing in yet another place, so that if one attempted to chase after what was behind all this, it would disappear in the middle. When they appear between spring and autumn, they　show up especially in hot summers and appear easily when it is cloudy when the weather is changing.

They are said to appear from between ten and several hundred in a line, and just when one thinks that they have increased, they would suddenly disappear then multiply once again. In the Nagano Prefecture, a ton of lights like that of a paper lantern would appear in a line and flicker.

The line's length spans across up to one ri (about 500-600m). Generally the color of the fire is red or orange, but there have been several examples of witnesses that have seen blue flames.

Concerning their location of appearance, in Tonami, Toyama Prefecture, they said to appear in the hillsides where there are no roads and other places where there is no presence of humans, but in Monzen, Fugeshi District, Ishikawa Prefecture (now Wajima), there are also legends where it is said to follow a human anywhere. It is often said that foxes trick humans, so likewise, the kitsunebi would light up places where there are no roads and make the humans lose their way. In Iida, Nagano Prefecture, it was said to be possible to disperse it when such a thing happens by kicking it up with one's feet. In Izumo Province (now Shimane Prefecture), there are legends about catching a fever after encountering a kitsunebi, giving a strong basis for the hypothesis that kitsunebi are like ikiaigami (divine spirits that brings misfortune from unprepared encounters with them).

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Wikipedia