Oni Hitokuchi appears in pre-medieval tales less as a fixed figure than as a term for a demonic being that fells a human with a single bite. It typically emerges in liminal scenes—at night, in thunderstorms, near storehouses or by the roadside—often intruding upon lovers’ trysts or flights. In The Tales of Ise (the Akutagawa episode), thunder drowns out the screams, and the lack of remains underscores the instantaneous “one bite.” Nihon Ryōiki and Konjaku Monogatari depict its mimicry as a man, serving as a warning against deviating from social bonds such as marriage or vows. After Sekien’s imagery fixed the name, folklore used it to reframe wartime, famine, and disaster disappearances as otherworldly devourings. Thus “Oni Hitokuchi” here is a type-name: its form is not fixed, and its essence is speed of consumption and absence of traces.