Her alleged brother was a soldier drafted to fight the xx army? Slaveowner MC-kun is an (ex)soldier from the xx army. So if her story is to be believed then this village is in enemy territory, and the xx army reaching here means this area has fallen under their control. The "sea of blood" was possibly caused by soldiers and not bandits.
But it could still be a made up story. This alleged bumpkin could've come from another country to live her serial killer dreams at a village just across the border or something. Anyway, there no way next chapter isn't going to be bloody now that their pursuers have caught up.