Onibi

Onibi (鬼火) is a type of atmospheric ghost light in legends of Japan. According to folklore, they are the spirits born from the corpses of humans and animals, and are also said to be resentful people that have become fire and appeared. Also, sometimes the words "will-o'-wisp" or "jack-o'-lantern" are translated into Japanese as "onibi."

According to the Wakan Sansai Zue written in the Edo Period, it was a blue light like a pine torchlight, and several onibi would gather together, and humans who come close would have their spirit sucked out. Also, from the illustration in the same Zue, it has been guessed to have a size from about 2 or 3 centimeters in diameter to about 20 or 30 centimeters, and to float in the air about 1 or 2 meters from the ground. According to Yasumori Negishi, in the essay "Mimibukuro" from the Edo period, in chapter 10 "Onibi no Koto," there was an anecdote about an onibi that appeared above Hakone mountain that split into two and flew around, gathered together again, and furthermore split several times.

Nowadays, people have advanced several theories about their appearance and features.

As onibi are thought of as a type of atmospheric ghost light, there are ones like the below. Other than these, there is also the shiranui, the koemonbi, the janjanbi, and the tenka among others. There is a theory that the kitsunebi is also a kind of onibi, but there is also the opinion that strictly speaking, they are different from onibi.

First, considering how the details about onibi from eyewitness testimony do not match each other, onibi can be thought of as a collective term for several kinds of mysterious light phenomenon. Since they frequently appear during days of rain, even though the "bi" (fire) is in its name, they have been surmised to be different from simply the flames of combustion, and is a different type of luminescent body. It is especially of note that in the past, these phenomena were not strange.

In China in the BC era, it was said that "from the blood of human and animals, phosphorus and oni fire (onibi) comes." The character 燐 at that time in China could also mean the luminescence of fireflies, triboelectricity, and was not a word that indicated the chemical element "phosphorus".

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