Ariel

Ariel (アリエル, Arieru?) is Haruna's teacher at Matellis. Matellis is a school where the Masou-Shoujo train. Currently, Ariel is the only known teacher. Haruna appears to be the 634,526,379th student, while Chris and Kyoko are both former students. Ayumu is also technically accepted to be one of the students as he does fight as a Masou-Shoujo for Haruna. She has an affinity for Kyoto-made tofu and sends Haruna to get her some due to her credit cards being overcharged. She is also known as Dai-sensei (大先生?, lit. "Great Teacher").

Ariel has whitish-light, blue hair and golden eyes. Her outfit seems to be a professor's uniform, mainly because of her occupation as a teacher. Despite her youthful appearance, she's easily over a century years old, as evidenced by her more mature demeanor when compared to her student, Haruna.

Ariel always smiles or is in a good mood, even when dangerous events occur. However, she sometimes takes risks. It is unknown what her true motives are, yet she is very protective of her students and will kill anyone who harms them.

It is later revealed that she had planned to overthrow Lilia Lilith, the Queen of Villiers, a century before the events of the series and appointed her mentor, Chris, as the leader of the coup. It ultimately failed, and Chris and a few others involved took the fall, with Chris herself cursed into the form of a middle-aged man. However, Ariel herself apparently managed to escape. She "reformed" for appearances' sake, but still strives to stop Villiers' constant warring with other kingdoms, especially the Underworld.