Ishinagenjo (Japanese: 石投げんじょ, "stone throwinggenjo") is a folkloric phenomenon which is documented to occur in theNishisonogi district of theNagasaki Prefecture, the waters ofEnoshima, and the city ofTosu in theSaga Prefecture.[2][3]
"In the month of May, the rainy season, a group of fishermen are working at night in the midst of a thick fog. Suddenly comes the sound of a huge rock crashing into the ocean, a tremendous splash and crack that sends the boat rocking and the sailors panicking. However, there is no rock to be seen, even by the break of day."[2]
In the Japanese Folklore Institute's bookComprehensive Lexicon of Japanese Folklore, the phenomenon is explained as being the doing of a sea monster - oryōkai (Japanese: 妖怪, variously translated as "specter", "monster", "goblin") - known as the Iso Woman or some other related sea witch. This explanation is echoed inKunio Yanagita's bookYōkai Lectures, in which Yanagita concurs that the phenomenon is best explained by some oceanicyōkai.[4] Because of this association, many experts have hypothesized that the "jo" - written inhiragana as "じょ" - actually means woman - represented by thekanji "女"[5][6] - which is the rendering used by folklorist Sakurada Katsunori in her paperGhost Ships and Drowning People.[3] Written thus, Ishinagenjo (石投女) translates literally to "stone-throwing woman". TheKojien, on the other hand, renders "じょ" as "尉", meaning "captain" or "old man". The "stone-throwing old man" (石投尉) is likened in the text of the Kojien to an old man idly throwing stones into the sea.[7] However, yōkai expert Kenji Murakami has expressed doubts regarding the existence of any documentary evidence to visually identify the creature responsible for the phenomenon described.[6] Indeed, the Kojien notes that it is assumed that fishermen only imagine seeing a monster, but that ultimately the experience as a whole is merely an illusion.[7]