In Princess Mononoke, an Emishi village is ravaged by a ferocious demon boar, forcing the young prince Ashitaka to defend his people. He kills the beast, but its dying curse seals itself onto his arm, granting him demonic strength while steadily draining his life away. Ordered by the village elders to travel west in search of a cure, Ashitaka reaches Tatara, the Iron Town, and is drawn into a brutal struggle over the forest that surrounds it.
Lady Eboshi leads Tatara's relentless drive for progress and deforestation, while Princess San and the sacred spirits of the forest fight to protect their world from human destruction. As their conflict intensifies, the balance between nature and industry begins to collapse, and Ashitaka finds himself caught between both sides. Determined to understand the pain and resolve behind each faction, he searches for a path toward harmony before the curse in his arm consumes him completely.