|Meaning||Blue heron fire|
|Other names|| Aosaginohi,|
|Places|| Nara Prefecture,|
|Book(s)||Konjaku Gazu Zoku Hyakki|
Aosagibi (青鷺火 or あおさぎび, Aosagibi) is a phenomenon illustrated by Toriyama Sekien in his Konjaku Gazu Zoku Hyakki. It depicts a night heron with a mysteriously illuminated body.
Many birds transform into magical yokai with eerie powers when they reach an advanced age. Aosagibi is the name for a bizarre phenomenon caused by transformed herons – particularly the black-crowned night heron. Other herons and wild birds, such as ducks and pheasants, are able to develop this ability as well, though it is most commonly attributed to the nocturnal night heron. This heron is found all along the islands and coasts, preferring remote areas with heavy reeds and thick woods. Aosagibi is most commonly seen at night in the trees where the herons roost, by the rivers where they hunt, or as the birds fly in the twilight sky.
Long-lived herons begin to develop shining scales on their breasts, which are fused together from their feathers. They begin blow a yellow iridescent powder from their beaks with each breath, which scatters into the wind. During the fall, their bodies begin to radiate a bluish-white glow at night. Their powdery breath ignites into bright blue fireballs, which they blow across the water or high in the trees. These fireballs possess no heat and do not ignite anything else, eventually evaporating in the wind.
Like most wild birds, night herons are very shy and usually flee from humans. Even after transforming into yokai, they retain their shyness. While the sight of a colony of wild birds breathing blue flames and making strange calls on a cool autumn night can be rather disconcerting, aosagibi does not post any threat to humans. However, because it appears very similar to other fireball-like phenomena, caution should be taken to avoid confusing aosagibi with oni-bi or other supernatural lights.