Eifer is a Dark Magus and member of the Black Cross organization in Rosenkreuzstilette Freudenstachel. Easily noticeable by the heavy clothes she always wears thanks to her hypothermia, Eifer is very cool-headed and mature for her young age. However, she can sometimes act out of character thanks to her violently fluctuating emotions and mood, but she seems to carry strong emotions towards Freudia Neuwahl for some unknown reason.
Her weapon is Eiferstachel, which allows her to manipulate the location, density, and hardness of the objects around her and use them to attack. She can turn earthly metals and flora into dangerous weapons to use in an instant.
Eifer was designed by Aburidashi Zakuro (zaku6). She is one of the winning entries of a boss design contest for Rosenkreuzstilette Freudenstachel so far, the others being Pamela Arwig, who was designed by alphes, Schirach Fühler, who was designed by Daddy (Tatei), Lecht and Rink Refraktia, who were both designed by REDMOON, and Doris Warmind, who was designed by Hissatsukun.