Natsuki Minamiya

Akatsuki Kojou's English teacher that claims to be 26 years old.

[Spoiler] She is an active attack mage and one of the few people who knows that Kojou is the 4th Progenitor. [/Spoiler]

She also assist Itogami Island Security with investigating crimes perpetrated by supernatural beings around Itogami Island.

[Spoiler] She is actually the guard of the magical prison that houses the most dangerous supernatural criminals; her actual body is sealed deeply in the prison, while it's actually an illusion that appears as a teacher and mage. [/Spoiler]

(Source: Wikipedia)