Princess Mononoke

In Muromachi-era Japan, the last Emishi prince, Ashitaka, kills a gigantic demon to protect his village, but his arm is afflicted by its curse. The demon, once the boar god Nago, was corrupted by an iron ball embedded in its body. Learning that the curse will eventually kill him, Ashitaka is exiled to the west, seeking a cure by uncovering the source of Nago's hatred.
On his journey, Ashitaka discovers that the curse grants him supernatural strength. He encounters a monk named Jigo, who advises him to seek answers in the nearby mountains from the Forest Spirit – a deer-like god of life and death that transforms into the giant Nightwalker at sunset. Guided by tiny kodama, Ashitaka passes through the forest of the gods, where he catches a glimpse of the Forest Spirit. Meanwhile, Lady Eboshi and her men repel an attack by a pack of wolves led by the wolf goddess Moro and her adopted human daughter, San.
Ashitaka arrives at Irontown, a settlement that has deforested the surrounding area to mine iron, leading to conflicts with the animal gods of the forest. The town shelters former prostitutes, who stoke massive furnaces, and people with leprosy, who manufacture firearms. Eboshi, the town's leader, admits to shooting Nago, instilling the hatred that corrupted him. She also reveals her plan to kill the Forest Spirit, hoping to eradicate the gods and enable Irontown to prosper. Ashitaka's cursed arm tries to kill her, but he resists its influence. Eboshi is collaborating with the mercenary Jigo, who stands to be richly rewarded for delivering the Forest Spirit's head – believed to grant immortality – to the Emperor.
The wolves attack; San, whom the townspeople call "Princess Mononoke", infiltrates Irontown and duels Eboshi. Ashitaka subdues them both and attempts to negotiate peace, but a townsperson shoots him. Strengthened by the curse, he takes San out of the town before collapsing. San threatens to kill him for sparing Eboshi, but is taken aback when he compliments her beauty. She brings Ashitaka to the Forest Spirit, who heals his wound but leaves the curse. The next day, a boar clan led by the blind god Okkoto declares its intention to attack Irontown, preferring to die in battle rather than witness their kind diminish. Ashitaka recovers and implores Moro to let San escape with him, but is banished from the forest instead.
The boars assault Irontown's forces but are annihilated by their weaponry. San and the mortally wounded Okkoto retreat to the forest, unknowingly followed by Eboshi and Jigo, who use the carcasses of the fallen boars to deceive Okkoto into leading them to the Forest Spirit. San tries to stop Okkoto, but his pain transforms him into a demon, engulfing her. With Moro's remaining strength, she and Ashitaka free San. The Forest Spirit grants peaceful deaths to Okkoto and Moro. As it transforms into the Nightwalker, Eboshi beheads it. Its body explodes into a dark, chaotic fluid that expands in search of its head, killing everything it touches – including the forest – and briefly reanimates Moro's head, which bites off Eboshi's arm.
Though reluctant to help the humans, San joins Ashitaka in pursuing Jigo to recover the Forest Spirit's head. Ashitaka evacuates Irontown as the Nightwalker's body floods it, and together, he and San fight Jigo for the head and return it to the Nightwalker. As the sun rises, the Nightwalker dies and dissolves into the wind. In its place, the devastated land is renewed with abundant flora, and Ashitaka's curse is lifted. A repentant Eboshi resolves to rebuild Irontown better, and Ashitaka chooses to remain and help. San, while admitting to Ashitaka that she loves him, is unable to forgive humanity and stays in the forest. They promise to meet as often as they can.