In a world where humans and spirits coexist, young warrior Ashitaka is cursed by a demon boar while defending his village. Seeking a cure for his cursed arm, Ashitaka journeys to the western lands and discovers the conflict between the ironworks led by Lady Eboshi and the animal gods of the forest, particularly the wolf goddess Moro and her human daughter San. Ashitaka learns that Lady Eboshi's ambitions to expand industry are causing significant damage to the sacred forest, fueling the animosity of its inhabitants and driving them into a prolonged battle.

As Ashitaka navigates through these opposing forces, he befriends both sides, hoping to broker peace amid escalating tensions. Lady Eboshi represents humanity’s drive for progress and survival, while San, also known as Princess Mononoke, embodies the fierce protection of nature. Caught in a war that threatens to destroy everything he holds dear, Ashitaka must garner understanding and compromise from all parties involved to save the forest and lift his curse. The fate of the natural world hangs in the balance as he endeavors to bring about harmony between humans and the ancient spirits.