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It is largely unknown of her background, but she was the former Alzano Empire's Imperial Court Mage Corps. At some point in the past, she adopted Glenn and took him under her wing, teaching him magic that she knows and uses today.
Celica suggested him to teach at the academy as a substitute teacher which Glenn denied immediately stating that he was not fit for the job, which Celica agreed that he didn't have a teacher's license. Glenn asked her to stop forcing reality into someone who acting cool, where Celica stated that he doesn't have a choice but to accept this offer.
Glenn questioned, if he rebelled about that where Celica threatened him whether he preferred to be struck by lightning, or be burned in a fire or be frozen in ice causing Glenn to fall at her feet pleading her to support him. Celica smiled at him and starts chanting the spell "Extinction Ray" causing a a thing ray of light which annihilated a part of the building. Glenn changed his mind, when Celica threatened him that the next one won't miss.
Celica sat at the top of the academy complaining about Glenn being late for his first day. Celica appeared behind Halley Astray, menacing him to not talk ill about Glenn in front of her, causing Halley to run away in fear. She apologised to the headmaster for Glenn's actions and said that she took full responsibility for Glenn's achievements and everything he does in the academy, putting her reputation at stake. The headmaster got surprised at her words and questioned her relationship with Glenn, which Celica replied with smile saying that she wanted him to have a good and full life. Later Celica sits at the of the academy roof sighing and thinking about how she persuaded Glenn to join the academy as a substitute teacher.
- ↑ Akashic Records of Bastard Magic Instructor episode 1