At the beginning of the movie, Yakul is seen galloping with Ashitaka on his back. Kaya warns them about something she saw in the forest. Yakul runs to the watch tower which Ashitaka climbs. The boar demon emerges from the forest covered in Demon Worms. Ashitaka commands Yakul to run away from the demon, Yakul too scared to run away freezes, Ashitaka then launches an arrow into the wooden pole next to Yakul, snapping him out of fear and he takes off. The demon soon rams into the tower, knocking it down sending the watchman and Ashitaka plummeting down to the ground. Ashitaka grabs the man and navigates them into a tree. Soon, Ashitaka and Yakul are reunited, and chase the boar demon down a hill. Yakul and Ashitaka run in front of the demon. Ashitaka shoots an arrow into its eye, causing the demon to roar in pain. It starts to chase Ashitaka and Yakul. Soon, Demon Worms invade Ashitaka's lower right arm. Finally, Yakul and Ashitaka slay the demon, and bring peace to their village.
Next, Yakul is seen with Ashitaka after his banishment. As they are about to leave, Kaya comes running toward them. She gives Ashitaka her crystal dagger as something to remember her by.
After, Yakul and Ashitaka lay eyes on the forest for the first time. They rescue two men, and discover tree spirits, a sign of good luck according to Ashitaka.
After, Yakul is seen carrying San, the wolf girl. Soon, San wakes up only to startle Yakul and send San flying off. Ashitaka and Yakul are brought to where the wolves live to spend the night but to leave in the morning. The next day, as Yakul and Ashitaka are heading to Irontown, Ashitaka hears San is in danger and goes looking for her. The emperor's samurai attack them in the process, Yakul is injured, causing Ashitaka to leave him behind. Yakul can't help but to be with his master, so he follows him until Ashitaka decides to bring him along. Once the pair is at Irontown, destroyed and under the attack of Asano's warriors, Ashitaka leaves Yakul in the hands of the men of the town.
In the end, Yakul is healed and is brought to Irontown.
- Yakul is compared to Bambi from the Disney film of the same name.