Gelda Nebilim once formed part of the Oracle Knights of the Order of Lorelei as Locrian Colonel, running the investigation under the orders of Fon Master Evenos into the relics known as Planetary Arte Catalysts, Six weapons that shared the power of Rem and Shadow, the Fonons of Light and Darkness.

After retiring from the Oracle Knights, Gelda Nebilim took her knowledge and opened a school in the Silver Town of Keterburg.

Unlike any teacher before her, Professor Nebilim shared an important bond with her students, and treated them like the children she never had. If there was something bothering them, she would step in and try to help.

After the arrival of Jade Curtiss as a young boy, Professor Nebilim felt the boy´s twisted mind of a mad scientist with no ability to distinguish the guilt or the pleasure of taking a life for smaller it was. She changed his heart however, and put him to develop his Fomicry methods towards a better cause.

Also, she taught a boy named Saphir, who was later obsessed with reviving her. She also concealed the sneaking from Peony the Ninth from his isolated mansion into the school to learn like the other kids and see his friends, since she knew it was even more important for an emperor to understand his people when Peony became the next emperor of the Malkuth Empire.