It was fifteen years ago, when people still believed demons and other mythical beast to be unfounded legends, fruit of wild imaginations and great ignorance of humans during the ancient times...

...but facts proved that it wasn't so.

The ancients weren't the ignorant ones, no, they were wise, wise enough to seal the threat before it could overwhelm them.

Wise, incredibly wise, and yet not wise enough to win against the power of time... or maybe they just underestimated their descendants foolishness?

Be it time or folly, fact was that modern humans in their own ignorance not only forgot their ancestor's teaching, but even regarded them as unfounded legends born out of ignorance about natural phenomenons and the world in general, and how could they not when science was progressing by the day?

Maybe such negligence and carelessness wouldn't have mattered much if that particular seal remained untouched, yet that same science and hunger for knowledge about the unknown that made humanity advance so much also proved to be their downfall.

A researcher found it, tinkered with it and even found the way to break it. Oh, so smart! Truly a genius to be able to understand something so mystical in such modern times, yet it was that same brilliancy that brought about a very dark age.

After being sealed up the demons never stopped preparing for conquest, drawing up many plans as they waited for the seal to come undone, yet they never expected humans to be as unprepared as they were.

Sure, science and modern weapon were great... yet they didn't fare too well against magic. Without a doubt humanity held the edge when it came to pure attack power... but when it came to defence, they were really pitiful, especially with so many civilians to take care of.

Demons on the other hand had no such scruples. Their magic defences could stand up to most assaults whereas their own attacks, while not as destructive as their opponents, were extremely versatile and variegated.

Five years, in just five short years the demons conquered the world and established their rule, relegating humans to the role of slaves.

Their aim were simple, males were to be used for labor while females were kept for breeding.

This last matter was especially looked upon by the demons, going as far as use their powers to affects the earth and especially the crops so that they'd bring about some special changes in human's constitutions... or to be specific in their females fertility.

After ten years of exposure to such influences, females became receptive to just about any seed and could come to terms in a matter of days or even hours, depending on the circumstances.

It was to the point where their wombs would be so overtly stimulated by semen that they may ovulate in response to a creampie, and even climaxing one too many time may let them pop out an egg... a true marvel from the demons, wishing to turn females in simple breeding tools, though as a side effect their eggs are somewhat more resistant to sperm and expire soon after.

However wombs weren't the only things that changed in those ten years.

Humans too adapted, most of them resigning to a life under the demons while some found ways to climb up the stairs of society to join the ruling class... but as a matter of fact, resistance and rebellion were never too far.

Many people secretly joined anti-demons organizations and while many of them got rooted out, there was no denying that more and more groups sprouted out like weeds.

It is one of those group that Roze joined when she was barely a teen, accepting their training and becoming the demon slayer that she was right now, capable of razing small settlements and even minor villages on her own... though this time it is her own home town at stake, and this metropolis is nowhere as small as her previous targets...