The Abura-akago (jap. 油赤子; transl. "oil baby") is a fictional being of Japanese folklore. He is a Yōkai and is usually described as sinister, but harmless to humans.
The Abura-akago is said to enter inhabited houses and temples at night in the guise of a hitodama (a type of spirit flame or will-o'-the-wisp) and assume the form of an infant or small child.
He is then said to search for oil lamps, similar to the Rokurokubi, and then drink them up, or lick them out with his long tongue.
He then steals the vessels and transforms back into a hitodama. Other lore tells of Akago meeting with other Akago, then having nightly parties in houses.
Various anecdotes and legends have been passed down about the Abura-akago.
In Shiga Prefecture, there is a legend that the akago is the spirit of a deceased oil merchant who repeatedly stole from the local Jizō temple and was therefore not allowed to enter the afterlife.
As a result, the cursed spirit of the thief had turned into a will-o'-the-wisp.
A similar legend is told in the former province of Ōmi: there the Abura-akago is said to wander the streets at night in the guise of a Hitodama, sucking the oil out of the lamps.
The local inhabitants believe that the Abura-akago is the reincarnation of an evil oil merchant, who during his lifetime had repeatedly stolen the oil from the street and courtyard lanterns.
Even after his death, he could not (or would not) stop stealing. Therefore, he was doomed to wander the streets and houses forever as a ghost, drinking lamp oil.