Wakan Sansai Zue
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 two or three centimeters in diameter to about 20 or 30 centimeters, and to float in the air about one or two 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.