O Goncho

This giant white winged dragon from the traditions of Japan. The O Goncho inhabited a particular stretch of water near Yamahiro. Every 50 years, it transformed into a golden bird with a cry resembling the howl of a wolf. This metamorphosis and the cry of the O Goncho were believed to passage imminent disaster.

John and Caitlin Matthews, The Element Encyclopaedia of Magical Creatures, 2013, O Goncho, p 351