Ryōmen Sukuna.

Ryōmen Sukuna (両面宿儺) is described as an extraordinary being with two faces and four arms, a body that marks him as more than human from the moment he enters the record. The doubled face suggests simultaneous perception and threat, while the additional arms signify martial excess. Even before later folklore developed him further, the court chronicle framed his body as evidence of dangerous abnormality.

In official memory, Ryōmen Sukuna opposes the Yamato order from the Hida frontier and must be subdued as a violent disruptive force. Later readings turn that opposition into something more fully demonic, casting him as a monstrous chief rather than merely an enemy chieftain. At the same time, some local traditions remember him less as a demon than as a powerful figure unjustly condemned by the center. His interactions are therefore political as well as supernatural: he stands where history, legend, and demonization overlap.

Ryōmen Sukuna first appears in the Nihon Shoki, where the court describes him as a fearsome two-faced being in Hida. That ancient textual witness is the core of the tradition. Later yōkai and demon-lore treatments amplify the monstrous reading, folding him into a broader Japanese habit of turning rebellious or marginal figures into oni-like adversaries. The result is not a simple folklore monster, but a figure whose demonic reputation grows out of state narrative and later legend-making.