She is a giant(Yaksha). Yaksha in Thai myth, they are huge, scary and powerful. One of their characteristic is 2 big protruding fangs. They can transform themself to be any creatures espacially human. This song is about Thai tragical myth called "Prarod-Mari". The story of the Meri(Yaksha)'s love with Prarod(Human). I can't remember all the story but at the end Prarod left Meri. She followed him and beged him the go back with her. But Prarod insisted to leave her so that makes her was so sad and died later.