Teiei is a nyosen (female sage) who lives on Mount Hou. She is among the fifty oracles dedicated to caring and protecting the young kirin (a creature that chooses the ruler of each kingdom) that is born on the mountain.

In The Twelve Kingdoms: Sea of Wind, she is the senior of the oracles on Mount Hou and acts as a mentor to Youka, the newest oracle on the mountain. She has been an oracle for hundreds of years, such that she is no longer certain of her age or how she became a nyosen. In spite of her appearance, she can be commanding, especially towards intruders appear on Mount Hou.

Her role is expanded in the anime, when she appears as a junior nyosen alongside Shoushun, an oracle from En who becomes close to Enki.

(Source: The Twelve Kingdoms wikia)