The year is 2500. The world is not what it used to be. One hundred and fifty years previous there was an enormous nuclear explosion that set off a chain reaction; exploding various power plants all over the world.
As everyone slowly began to die of the poison in the air, the animals began to mutate, adapting to the new atmosphere. They grew bigger, stronger, more aggressive. They changed into creatures that looked more like aliens than wildlife. They attacked the cities and the towns. Anywhere that there were people, they attacked, until it wasn't just the poison that was making the human species decline.
The top scientists created a vaccine that was supposed to make human beings immune to the effects of the radiation. It took them only a few weeks, and they didn't have time to do many tests.
But it worked.
Until the women began to have reactions to the drug. The population of women to men ratio dropped from almost 50:50 to 25:50. And then even further to 10:50.
The scientists reworked the drug until it was safe for every man woman, child and animal to use. The population once again began to grow, despite the buildings and the world around the human species collapsing. But by then it was too late.
Women were so rare that the men decided to round them up; keep them locked up to keep them safe from crime, or dangerous, desperate men.
Over time, the simple act of keeping women inside to protect them warped and changed, until society was a completely different thing compared to how it was previously. The women had grown in numbers, but still not enough to equal the amount of men.
And women were no longer free. During the process of protecting them, they had been given rules that had gradually grown more enforced and restricted over time. They were used as slaves to the men; they were their property to use as they would.
Once born, a females fate was already sealed. While boys were taken from their mothers and raised separately; being schooled and taught how to fight, girls were taught by their mothers how to act respectfully and how to live in the world under the rule of their master.
Once they were of age, by law they were to be taken by the government and placed in an auction for whoever wanted to buy them. The only saving grace that they had was that they were not allowed to be touched sexually by a man until they were brought legally; but this was only to ensure that any offspring would come from a strong body and would survive.
A womans job was to serve in any way told, and to produce healthy children.
Any women that disobeyed, would be punished severely.