Blood Lad
Summary
Staz is the vampire boss of a section of the demon world, but he has little interest in human blood. He's more infatuated with Japanese culture. When he learns that Yanagi Fuyumi, a Japanese teenage girl, accidentally wanders into the demon city, he jumps to the occasion. However, while Staz deals with an intruder on his turf, the oblivious Fuyumi is killed by a monster and becomes a wandering ghost. The disappointed Staz vows to her that he will find a way to bring Fuyumi back to life.
In a system like that there would need to be rigorous documentation and certificates of prior ownership/guardianship or else anyone and everyone would just get grabbed off the street and enslaved at any time, and such a society would collapse instantly. So these slavers wouldn't have such documentation unless it was a forgery since the kids were just kidnapped; both offenses should be very serious capitol crimes. Once again, the day is saved by glorious Bureaucracy! (and the MC's knowledge and exploitation there of).