San is the titular character of Princess Mononoke (although she is arguably not the protagonist).
When San was a baby, the wolf goddess, Moro, attacked her parents who were found damaging the forest. San's parents threw her to Moro as a sacrifice to save their own lives. Moro raised San as her own daughter, and in turn San treats Moro as her mother and Moro's two natural pups as brothers.
San’s primary concern is protecting the forest and the animals she lives with. She rejects her own humanity and even thinks of herself as a wolf. She has attempted to assassinate Lady Eboshi of Irontown many times, as she believes that Eboshi’s death will result in the end of Irontown and human growth into the surrounding forest. It is only by Ashitaka's affection to her that she slowly comes to acknowledge her human side as well.
After the battle for the Forest Spirit's head, San tells Ashitaka that he is very dear to her. However, she cannot forgive the human race for what they have done to the forest and will continue to live apart from them. San returns to the forest while Ashitaka remains in Irontown. Although, before separating Ashitaka promises that he will always be near and he will visit her in the forest whenever he can, and she agrees.
San is a 15 year old girl who wears ragged clothing and a cape made of a wolf's fur. She has what appears to be red war paint in red dagger blade shaped stripes down her face. Her hair color is light brown and it's short and slightly messy. Also she is very agile, fast and she appears to be really good in using daggers and spears.
She later wears Kaya's Crystal Dagger after Ashitaka gives it to her as thanks for saving him.
San and Ashitaka first meet by the river, where she is treating a wounded Moro. Later that night, San attacks the village to kill Lady Eboshi, only to be stopped and knocked unconscious by Ashitaka. As he tried to get her out of the village he receives a lethal gun shot. Originally wanting to kill him for stopping her from killing Lady Eboshi, she decides not to after Ashitaka admits to her that he finds her beautiful. This is thought to be because Moro thinks she is ugly, since she is truely a human, not a wolf. It is probably the first time anybody has called her beautiful, so she takes pity on him. She later transports him to the Forbidden Forest, where the Forest Spirit heals him, and she stays with him until he recovers. As the movie continues San starts to develop feelings for Ashitaka and later she falls in love with him. Ashitaka gives her a crystal dagger that Kaya give him, which she is to treasure. After giving the spirit's head back, she decides to live in the forest being unable to forget what human's did. Ashitaka reveals that he will live in Irontown (since he was exiled from his own village) but he will always be near. San reveals that he means much to her and that she will miss him but Ashitaka promises that he will always visit her in the forest whenever he can and San agrees.