Case file · High strangeness
Shiranui, the unknown fires of the Yatsushiro Sea
The Nihon Shoki says the legendary Emperor Keikō, sailing by night, was guided by fires of unknown origin; the lights still appear on the Yatsushiro Sea around Obon.
720 CE · 32.55, 130.50 · status: explained
The account
Rows of lights appear far out at sea, multiply and split. The name Shiranui means 'unknown fire', and the region took it as a poetic name for Higo.
The sceptical view
Studies since the 1930s explain the lights as a mirage: fishing lanterns refracted by layers of warm and cold air over tidal flats. They became rare as the flats were reclaimed and lights changed.