An elderly couple in the isolated mountain village of Nagakushi received two infants — a boy and a girl — as foretold in a dream sent to the childless couple. The children grew up together, unremarkable in most ways until the western capital fell to an evil dragon whose power converted humans into oni: soul-consuming ogres. The oni spread outward from the capital and reached Nagakushi, stripping the souls of the elderly couple who had raised the children. Effectively orphaned, the boy and girl set out from the village to recover what was taken. The journey revealed, by its end, what neither of them had been told: the truth of where they actually came from, and why they had been sent to this particular village in the first place.