Valteishia, also known as "Valteishia of the Sun and Solitude," leads Absolute Angel Megingjord under her command. She has lived through multiple deaths and reincarnations in her current fourth body. Currently, she is accompanying Kazuya and serving as his loyal follower. At his request, Valteishia suppresses Kūs memories of their time with Kyoshiro and stuns Setsuna so he can take her away. It's worth noting that Valteishia has feelings for Kazuya.
Valteishia explains how the original Absolute Angel Cielo was separated into four beings, one of which further divided into its body and spirit. Kū is the body of that one Absolute Angel, while Valteishia represents its spirit. Since she lacks a physical form, Valteishia's consciousness was transferred into a Steel Angel body by Kazuya, resulting in her current appearance. Despite this, Valteishia longs to be reunited with Kū, although she may have some regrets about certain actions taken by both herself and Kazuya during the series.
After the conclusion of the story, Valteishia assists a wheelchair-bound Kazuya, who seems to be dealing with some form of mental trauma. Her design is inspired by Valkyrie from the UFO Princess Valkyrie anime and manga series.