Hm...I like the art and the characters are cute, but the story seems a bit pointless to me. Why take revenge if the people who burned witches lived hundreds of years ago?
According to some feminist scholars, the European witch hunts were a symptom and a manifestation of the new capitalist and nationalist societal order's drive to re-subjugate women and to confine them to the homemaker role that was viewed by this new order as necessary to support the man as bread-winner. (Of course, history showed that this idea fell apart as soon as the demands of the growing industry forced women (and children) to work alongside men, but even then, they were still expected to pull a double shift at work and as homemakers.) Anyway, this subjugation was carried out using terror tactics, such as public executions of the most educated and thus powerful women of society, referred as "wise women" or "witches", and when they ran out of those, they continued with random girls until European women were effectively beaten into silence and submission (for a while, at least).
With this in mind, it would be interesting to see if the "revenge" the teachers speak of in this manga is actually aimed at upending the modern nation-states and the global capitalist elite, both of whom ended up profiting the most from witch-burning. The fact that the witches' surreptitious survival is explicitly linked to them entering the service of future nation states gives me some hope, but then again, I don't really expect a Japanese manga artist to express a radical left agenda in a story about magical lesbians.
The theory sounds like a very...creative interpretation of history.
