Okubi

Shiranui are a specific type of kaii known as a kaika(mysterious fire). They appear in bodies of water around Kyushu on dark, calm nights—particularly at the end of the 7th month according to the old lunar calendar. They are most visible during the strongest ebb tide, around 3 am, and appear roughly 8 to 12 kilometers off shore. They can be seen from elevated parts of the coast, but not from sea level.

Shiranui begin with one or two distant fireballs, called oyabi, floating just above the surface of the sea. The oyabi sway left and right, splitting apart and multiplying until finally there are hundreds or thousands of fireballs swaying in the distance. This line of fireballs can stretch out for many kilometers.

Shiranui were thought to be manifestations of the lanterns created by Ryujin (the dragon god of the sea) . On days that shiranui appeared, local villages were forbidden to catch fish in the same area as the kaika. Boats that tried approaching shiranui reported that no matter how long they sailed, the fireballs remained far away on the horizon.