Navi has the appearance resembling what Echo will potentially look like in the future. That is, a tall, beautiful young woman with a large bosom and curvy figure, long pink hair, and horns on her head. She tends to wear a light-colored dress resembling a robe of some sort. She has marks resembling a Seikoku over much of her body.

(Source: Wikipedia, Seikoku no Dragnar Wikia)