She is voiced by Rie Ishizuka in the Japanese version of the anime and Clarine Harp in the English version.
Undine has long, pale hair which she tucks behind her ears. She wears the standard Claymore uniform. Undine appears as a bulky, muscular woman, however this is a result of shapeshifting. In her true physical form, she appears the most frail of Claymores. She is 175 cm tall, a height typical of a Claymore.
Undine was notably brash and aggressive. She was particularly harsh towards weaker Claymores. She considers them to be nothing more than impediments to her mission, but later it is revealed that she only wanted to protect those weaker than herself. She appeared to be a loyal friend as she carried her deceased friend's sword in her dominant hand and held onto it with great care. Even after getting kicked by Deneve, she refused to let go of it.
Despite her tough attitude, she has the extreme fear of pushing herself too far and awakening.