In the summer of 1749, in the castle town of Miyoshi in Bingo Province (today's eastern Hiroshima), a sixteen-year-old named Inō Heitarō sat through thirty straight nights of hauntings in his own house. On the final night, the thing behind it all finally showed itself. It called itself Sanmoto Gorōzaemon, a maō, or demon king, who ruled over lesser yokai the way a lord rules over vassals. It had come, it said, to settle a bet. It had lost.
The record of those thirty nights survives as the Inō Mononoke Roku, one of the strangest documents of the Edo period (1603–1868): a dated account of a haunting, written as if it really happened to a real family.
What does Sanmoto Gorōzaemon look like?
Illustrated copies of the Inō Mononoke Roku do not draw Sanmoto Gorōzaemon as a monster. He arrives on the last night as a samurai of about forty, in formal kamishimo dress. He sits with calm dignity, more official than fiend. He commands a following of countless smaller creatures. One scroll hints at his true form: a huge hairy leg sticking out of his palanquin. The horror had already come from thirty nights of smaller apparitions, not from him.
His name is itself a small puzzle. The characters 山本 are almost always read Yamamoto in Japanese. In this tale alone, tradition insists on the unusual reading Sanmoto. Paired with 五郎左衛門, an ordinary Edo-period man's name, the whole thing reads less like a monster's title and more like a person's business card.
Thirty nights of hauntings
Each night of the ordeal brought something different. On the first night, a hairy giant grabs Heitarō. A woman's severed head flies at him, laughing, and licks his face. A giant old woman's face stares down from the ceiling. Later, things stick to the ceiling as if gravity has flipped.
None of it drove Heitarō from the house. He kept his nerve, night after night.
The wager revealed
On the thirtieth night, Sanmoto Gorōzaemon explained the point of it all. The whole haunting had been a test, and a wager. He and a rival, Shinno Akugoro, were competing to lead the demon kings. The winner would be the first to frighten a hundred brave youths. Heitarō was meant to be number eighty-six. His nerve cost Sanmoto the bet, and now he had to start over.
Impressed rather than angry, Sanmoto Gorōzaemon praised the boy. In many versions, he also gives him a wooden mallet. If Shinno Akugoro ever attacks, he says, strike it. Sanmoto himself will come to help. Then he left, leading his whole crowd of yokai.
Where it comes from
The Inō Mononoke Roku is unusual among Edo-period kaidan (ghost stories) because it names a real place, a real family, and a real date: Miyoshi, in Bingo Province, in 1749. The Inō family kept a copy of one version for generations. Illustrated scrolls of the tale circulated for decades afterward.
It can be read less as a report of an actual haunting and more as a coming-of-age story dressed as one. A boy proves his composure against escalating fear, and a demon, of all people, is the one who certifies it. The wager framing does real work here: it turns a string of frightening images into a single test with a winner, which is rarer in yokai literature than it sounds.
Sanmoto Gorōzaemon today
The tale's hometown has not let it go. The Miyoshi Mononoke Museum, which opened in Miyoshi, Hiroshima Prefecture, in 2019, was built around the yokai art collection of Yumoto Kōichi, a yokai researcher and collector, and gives the Inō Mononoke Roku a central place among its exhibits. Visitors can see reproductions of the same scrolls that recorded Heitarō's thirty nights, in the same region where they are set.
