An elderly couple in the mountain village of Nagakushi received two infants — a boy and a girl — as foretold in a dream, raising them as their own. When the children were eight, an evil dragon appeared in the western capital and began converting humans into oni: soul-devouring ogres that spread outward from the city. The oni reached Nagakushi and stripped the souls from the elderly couple before the children could intervene. Unharmed but effectively orphaned, the two set out from the village to save the only parents they had ever known. Part 1 of the adventure follows their journey as it begins — from the mountain village, through the first obstacles, toward a dragon whose power they do not yet fully understand.