Orochi, the Eight-Headed Dragon(1994)

Original title: ヤマトタケル

After killing his brother, Prince Yamato is banished from his father's kingdom until he can bring his dangerous powers under control. On his journey, he meets and joins with the magical priestess Oto, and together they go to fight against an evil god that has been ravaging the Earth in the form of an enormous hydra. Will Yamato ever return home to reclaim his rightful place on the throne?