shiranui

Shiranui (不知火, unknown fire, Shiranuhi in the historical kana orthography) is an atmospheric ghost light told about in Kyushu. They are said to appear on days of the noon moon such as the kaijitsu (29th or 30th day) of the seventh month of the lunisolar Japanese calendar when the wind is weak, in the Yatsushiro Sea and the Ariake Sea. The phenomenon persists in the present day, with the strange lights having been determined to be an atmospheric optical phenomenon.