Onikōbe — The Legend of a Place Name Born When a Slain Demon’s Head Flew There

Deep within the Naruko Onsen hot spring region of Osaki City, Miyagi Prefecture, lies a place called Onikōbe (鬼首), literally “demon’s head” — a name almost no one can read correctly without knowing it first. According to legend, the place is named for an unusually vivid origin: it’s where the severed head of a slain demon came flying down and landed. Today this area is known for its geysers and hell valleys as a tourist destination, so why does it carry such an ominous name?

Origin — The Place Where a Slain Demon’s Head Came Flying

According to legend, in 801, during the Heian period, the shogun Sakanoue no Tamuramaro, dispatched by the imperial court to subjugate the Emishi people, killed a local chieftain named Ōtakemaru, said to have ruled this entire region. The story goes that Ōtakemaru’s severed head flew all the way here and fell to the ground, giving the place its name Onikōbe (“demon’s head”), while the spot where his body was buried came to be called Onishigai (“demon’s corpse”). In records written from the imperial court’s perspective, Ōtakemaru is portrayed as a “demon” who deserved to be subjugated — but that label belongs only to the victors who wrote the history. To Ōtakemaru himself, this land was surely not a conquest, but his own home.

Those Called “Demons” — The Subjugation of the Emishi

Sakanoue no Tamuramaro’s subjugation of the Emishi left behind countless place names and legends across Tōhoku in the form of “demon-slaying” stories. What they share in common is that local forces who resisted the imperial court are cast as the ones being subjugated, under names like “demon,” Akuro-ō, or Ōtakemaru. Tōhoku at the time was home to its own distinct cultures and communities beyond the reach of Yamato court rule — people the center regarded as “unsubmissive folk” or “demons,” but who, from their own point of view, were simply trying to protect their land and way of life. The place name Onikōbe stands as living evidence that the memory of that history of conquest is still carved into this land, in the form of a name, more than a thousand years later.

Onikōbe Today — What the Hell Valley and Geysers Tell of the Land’s Memory

Today, Onikōbe is a beloved hot spring area within the Naruko Onsen region. Hot springs here are said to have already been discovered as far back as the era of Emperor Ōjin (around the 3rd century), and records show the springs were used by the Date clan during the Edo period. The area’s biggest draw is its collection of geothermal fields named after “hell,” led by Fukiage Jigokudani, where springs near 100°C erupt one after another right beside a riverside walking path, alongside Katayama Jigoku, Okunoin Jigoku, and Arayu Jigoku. Best known of all is the Benten geyser at Fukiage Onsen, famous for shooting water 15 to 20 meters into the air every 10 to 15 minutes. Knowing the legend, there’s something more than mere natural phenomenon in the image of hot energy still erupting from underground, on the very land said to be where a slain demon’s head fell.

Reflection — A Loser’s Memory, Carved Into a Place Name

From here on, this section reflects our own speculation. Most “demon-slaying legends” found across Japan are simply the conqueror’s own record, taking hold as accepted history. But we suspect the reason the name Onikōbe has survived for more than a thousand years isn’t only to celebrate the imperial court’s victory — it may be because the people of this land refused to let the defeated side’s existence be erased, and kept their memory alive in the form of a place name instead. If unsubmissive people truly did live on this land, then to them, Sakanoue no Tamuramaro would have been the very thing to fear: the man who burned their homeland and killed their leader. And yet, what survived as place names are the words for the vanquished side — Onikōbe, Onishigai — while no place name preserves the name of the conquering general. There is a strange twist and depth to this legend in the fact that, even while told as a story of the victors, what actually got carved into the land was the trace of the losers.

One could read the hot springs and geysers still erupting from the hell valley as evidence that the anger and regret of the slain still burn on underground. That said, this is only our own imagination at work, and it goes without saying that the phenomenon is fully explained by volcanic geothermal activity as a matter of natural science. Even so, it may be precisely because the natural phenomenon and the local legend appear to overlap that Onikōbe has remained in people’s memory for more than a thousand years.

Notes for Visitors

Geothermal areas like Fukiage Jigokudani are natural terrain where high-temperature springs erupt right beside the walking path; leaving the path or approaching a vent risks serious burns. Always follow posted signs and fences. The walking path may be closed in winter, so check the latest operating status before visiting. This article is published to document the site, not to encourage visiting it — please remember this is an actively volcanic landscape, not merely an entertaining backdrop for a legend.

Related reading
Yagiyama Bridge (Tatsunokuchi Gorge) (Aoba / Taihaku Ward, Sendai)
Namahage — The Visiting Deity Long Mistaken for a Demon

Frequently Asked Questions

Q. Is the place name Onikōbe really derived from a demon’s head?

A. It’s a legendary origin. It comes from a tradition that the severed head of a chieftain named Ōtakemaru, killed by Sakanoue no Tamuramaro, flew to this spot and fell — there is no historical record confirming an actual demon’s head.

Q. Can you still visit Onikōbe today?

A. Yes. It’s a hot spring and tourist area within the Naruko Onsen region, and walking paths such as the one at Fukiage Jigokudani are open to the public. Because it’s a high-temperature geothermal area, visitors must follow all posted guidance.

Q. Has KARASU CHANNEL filmed at Onikōbe?

A. No, we haven’t filmed there yet, though we’re considering it. You can watch our footage from other haunted locations and ghost stories on our YouTube channel, KARASU CHANNEL.

Japanese horror 鴉番組