Sōma

is a demon that consumes memories from its victims.

Background
Four-hundred years ago, Sōma almost destroyed the Daidai village, leading them to waste away. It was confronted by a shrine maiden named Kuen. It managed to take possession of Kuen's body, but Kuen managed to seal it inside the rock. However, despite that Sōma was sealed away, its portion stayed within Kuen, resulting in a curse that was passed down to her descendants.

Appearance
Sōma is a horned-skull demon spirit.

Legacy
When two bearers of the curse reach age twenty, the curse manifests a mark on the palms of their hands, signalling they connect Sōma with the outside world, and they slowly have their memories drained. Every hundred years, the seal restricts Sōma weakens and its horns begin growing from the rock and it becomes stronger. In order to prevent Sōma from escaping the seal, a man and woman, who bear the curse, must be wed to reapply the seal.