Bakotsu

The sources identify the Bakotsu as the spirit or animus of a horse that died in a fire and record it as one of sixteen yōkai illustrated in the Tosa Obake Zōshi, an Edo-period obake/zōshi pictorial roll. Beyond this classificatory identification, the cited materials supply no narrative origin, lineage, or mythic tale about the Bakotsu; there are no recorded folkloric accounts, origin myths, or expansion of its backstory in the provided sources. Its 'origin' in the available record is therefore the Tosa Obake Zōshi entry itself, which names and illustrates the apparition rather than recounting a fuller tradition.

In the available sources the Bakotsu is described and pictured as a skeletal, flaming horse. The entry emphasizes exposed bone (reflected in the kanji 馬骨, "horse bone") combined with imagery of fire; no further anatomical details, coloration, scale, or additional physical attributes are recorded in the cited materials. The depiction is strictly iconographic: a horse reduced to its bones and shown with flames, consistent with Edo-period yokai illustration conventions.

The cited sources do not attribute specific powers, behaviors, or interactions to the Bakotsu beyond identifying it as the spirit of a horse that perished in a fire and depicting it visually as skeletal and flaming. There are no recorded accounts in the provided materials describing how it acts, whether it harms or aids humans, or whether it exhibits any supernatural functions; any such attributions would be speculative and are not in the sources.