Each samurai kept a stable of males, collecting them from other females and trading them with their favorites in the way a human might show dogs. Simple-minded and loyal, the ninjas could be set to tasks for which they would be rewarded with an opportunity to breed with the samurai.

When the disc touched her skin, the cold sliced through her skull and made the roof of her mouth ache. It would monitor her actions and ensure no cheating occurred. The final trials for the prospective child-bearers differed every time, which didn’t stop people from trying to guarantee that their genes were the ones passed down.