nova (rayearth)
A character from Magic Knight Rayearth anime season 2. She never appeared in the manga.
A mentally-unstable girl who harbors a yandere-like affection for Shidou Hikaru, and is an anime-only villainness. Her real nature isn't revealed until later:
Nova is a shadow of Hikaru's heart, born from the grief of having to kill Emeraude.