Sea apparition that echoes with falling rocks in the mist
Ishinagenjo
In the bottom of the mist, an impossible cliff rises. The boat turns back at the crash, and at dawn the sea is only calm water again.
Overview
Ishinagenjo is a sea apparition from the island-rich waters of northern Kyushu. On misty rainy-season nights, fishermen see what looks like a small island or rocky shadow, then hear rocks crashing down where no rock exists.
Encounter
A fisherman goes out on a damp, fog-heavy night. Through the mist a rock face seems to appear, then a loud collapse rings out. When he returns in clear weather, nothing unusual is there.
Lore
It is told around Enoshima in Nishisonogi, Nagasaki, and Ejima in Tosu, Saga. The Comprehensive Japanese Folk Vocabulary and Yanagita's Yokai Dangi treat it as related to sea-woman yokai such as isonade or iso-onna.
Traits
It has no stable body, instead showing phantom reefs or islands in the mist and frightening boatmen with the roar of falling stone. By morning it leaves no trace.
Suddenly, the sound of a great rock collapsing is heard.
Yanagita Kunio, Yokai Dangi