Derived from the Konjaku Monogatari tale of the “Board Demon,” this is a case of animated boards causing a haunting. Planks jut from beams or latticework inside a house, elongate, and crush people to death. Here “oni” means a broad class of uncanny phenomena rather than a horned demon. The stories stress that it targets those unarmed, serving as a cautionary tale for night watch duty.
Folklore & Legends
One summer night, two young guards on duty noticed a board protruding from a roof beam. It stretched seven to eight shaku and shot forward. Avoiding the two men who stood ready to strike, it slipped through the lattice and crushed five sleeping in the inner rooms. When the guards rushed in, the victims had been suffocated, and the board had vanished without a trace. From then on, warriors were warned never to part from their swords, and the tale was told to instill vigilance during night watch.
Yokai Cards1
Ita-oni (Board Demon) across multiple art-style decks
Drawing on the Konjaku Monogatari-shū, later scholarship calls it “Ita-oni” (Board Ogre). The entity is either a board itself or a phenomenon dwelling in a board, taking a plank-like form that juts from roof beams or lattices. Its motive and will are unstated, but its core act is crushing sleepers to death. In Heian court and aristocratic residences, night watch and gate duty were crucial, and tales of the uncanny often served to reinforce discipline. Here too, it bypasses two armed men and strikes a defenseless sleeping place, embodying the ethic that negligence invites death. While it aligns with the idea of spirits inhabiting objects, it lacks tales of aging into autonomy or growth, and is told as a transient manifestation of a specific board appearing to suit the scene. There are no records of pursuit or capture, and it appears and vanishes swiftly without leaving traces.
Character Profile
This section is our own creative profile for storytelling. It is not historical fact or scholarship.
understood to avoid those who stay alert and never set aside their arms
Abilities
extends and contracts its board-like bodyinfiltrates lattices and gapscrushes with strong pressureappears and disappears quickly without leaving traces
Weaknesses
tends to avoid armed individuals, maintaining lights and vigilance is said to reduce encounters
Habitat
roof beams and latticework of the imperial court and aristocratic estates, guard posts and sleeping quarters
The diagram below is a diagnostic evaluation chart for Canon-Concordant (Based on Tradition). The higher the value of each item, the stronger that characteristic is expressed.
