Rōjinbi

The rōjinbi is attested in Edo-period compendia of strange phenomena (notably Ehon Hyaku Monogatari) as an onibi or supernatural fire encountered deep in the mountains and at provincial boundaries. Later Edo commentary links certain accounts of rōjinbi to tengu traditions (e.g., writings cited in Heisuiroku and Senkyō ibun), describing the fire either as a distinct spectral phenomenon or as an onibi lit by tengu (tengu no miakashi). The primary documentary locus is the Edo bestiary tradition rather than a single cohesive mythic origin story.

Described consistently as a luminous, onibi-type flame or ghostly light seen at night — especially on rainy nights — in deep mountain locales or at provincial boundaries (notably the Shinano–Tōtōmi boundary). Sources emphasize that the light appears together with an elderly person (hence the name 'old person fire') and is experienced as a roaming light on roads rather than as a humanoid figure.

Accounts record that rōjinbi cannot be extinguished by ordinary water but can be put out by beating it with animal skins. When encountered on a straight stretch of road, holding one's footwear over one's head reportedly causes the flame to veer off to another path; conversely, if a person panics and runs, the rōjinbi is said to pursue them indefinitely. Some sources present it as an onibi produced by tengu activity (tengu no miakashi), which is used to contextualize the animal-skin cure in tengu-related lore.