Valteishia

ワルテイシア

Valteishia, who refers to herself as "Valteishia of the Sun and Solitude," commands the Absolute Angel Megingjord. Having died and been reincarnated numerous times, she is currently inhabiting her fourth body. She serves as Kazuya's current companion and loyal follower. Acting on Kazuya's orders, she apparently suppresses Kū's memories of her time with Kyoshiro and stuns Setsuna to allow him to take her away. Additionally, Valteishia likes Kazuya.
When explaining how the original Absolute Angel Cielo was divided into four beings, Valteishia clarifies that one of those entities was further split into body and spirit. Kū represents the body of that Absolute Angel, while Valteishia is its spirit. Deprived of her own body, this spirit was transferred by Kazuya into a Steel Angel body, becoming the current Valteishia. Valteishia apparently longs to be reunited with her 'vessel', Kū, though she seems to regret some of Kazuya's actions and her own involvement in them. Following the series, she assists a wheelchair-bound Kazuya, who appears to suffer from some mental damage.
Her design is adapted from Valkyrie, of the anime and manga series UFO Princess Valkyrie.