Mount Osore (恐山, Osorezan, 'Fear Mountain') in northern Aomori Prefecture at the top of Honshū is one of the three most sacred sites in Japanese Buddhism and — according to the longstanding tradition of the region — the location where the spirits of the dead cross over to the next world. The active volcanic caldera, last erupting in 1787, is traversed by the Sanzu River (the Japanese analog of the Styx), whose waters are said to be the last that the dead must ford. The caldera floor is a sulfurous wasteland of bleached stone, steaming fumaroles, and bright yellow crystalline deposits. An eighth-century Buddhist temple, Bodai-ji, sits at the shore of Lake Usori and operates as the gateway between the living and the departed.
Osorezan's signature phenomenon is the annual Itako Taisai — the Great Festival — held in July and October, when blind female shamans (itako) gather at Bodai-ji to channel the voices of the recently deceased for pilgrim families. The itako tradition dates to the Heian period and remains one of the few continuously-practiced forms of shamanic necromancy in the developed world; families travel from across Japan to speak through the itako with a son lost in war, a mother who died without final words, a miscarried child. The mountain's volcanic soil is credited with the ease of passage — the dead are said to be audible through the fissures themselves.
Outside festival time, Osorezan produces a catalog of individual paranormal reports: footprints of children appearing and disappearing in the sulfurous stone; voices calling travelers by name from the lake; and the sensation of being followed by one's specific departed relatives through the temple's inner yard. Small cairns of stones — left by bereaved parents to help the souls of deceased children complete the crossing — are routinely found rearranged or augmented overnight by no visible hand. Modern Japanese paranormal researchers, Shinto priests, and Buddhist scholars alike treat Osorezan as the genuine article: a place where the boundary between worlds is thinner.