青鷺火 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.