Oiran Buchi (花魁淵, 'Prostitute's Gorge') is a steep-sided ravine on the Ichinose River deep in the Tanzawa Mountains of Yamanashi Prefecture, west of Tokyo. According to the region's oral tradition — first recorded in written form in a 1910 collection of Kōshū-road folktales but drawing on earlier nineteenth-century accounts — 55 courtesans attached to the Kuromegawa gold mine were massacred at the gorge in the closing years of the Edo period, possibly 1868. With the mine's gold veins exhausted and its closure imminent, the mine's managers are said to have constructed a platform over the river for a final festival and, as the courtesans danced, cut the supports and dropped all 55 to their deaths in the water below — both to silence witnesses to the mine's secrets and to avoid the cost of relocating the women.
The gorge is remote: accessible only via a single-lane mountain road that continues north from the hamlet of Enzan, it sees few casual visitors. But a stone memorial marker erected in 1933 by the local Buddhist sangha records the story in precise detail, and the local Yamanashi Prefectural Historical Association accepts the general outline as likely historical. Modern hikers, photographers, and paranormal researchers visiting Oiran Buchi after dark routinely report a concentrated field of phenomena: the sound of women's laughter and music from above the gorge, cold drafts rising from the water in windless conditions, the smell of burning incense, and — most persistently — the impression of a long-sleeved garment brushing against the legs of those who stand too close to the edge. A JR East track-maintenance worker reported in 2004 that a woman in seventeenth-century courtesan dress had 'stood beside' him on the railway cutting above the gorge for perhaps ten seconds before evaporating.
Oiran Buchi is now a standard location in Japanese paranormal travel guides and produces more consistent first-person reports than nearly any other Honshū mountain site. Local Shinto priests perform annual pacification ceremonies at the stone marker each April, and by local custom no visitor should speak aloud while crossing the bridge above the gorge.