Appears in Toriyama Sekien’s illustration collections and in Ehon Hyaku Monogatari, and was widely known by the late Edo period. In Yamato, blue flames were said to appear on a great willow, and when approached the entire tree glowed blue. On Sado, a “dragon lamp” descended on a temple plum tree; when shot down, it proved to be a heron. The Wakan Sansai Zue notes that a goisagi flying on a moonlit night can look like fire. Other tales say an old black-crowned night heron emits a bluish light in autumn, or even turns into a floating fireball.