Earu is Princess Adena's guide.
It later leads them to Adena in the Labyrinth and then guides the party out.
As the party ventured to the "Castle of Dark Illusions" on the airship, they were attacked by monsters. Earu jumped out in front of one of their attacks, saving Yugi, but causing herself to be killed.
At the end of the game, Adena transformed into the "Mystical Elf" and revived all the fallen adventurers, including Earu.