It would sound like a joke in poor taste to say it with any other series, but since this is what it is, perhaps Anna is an M and this is actually her thing. There's no way Kuga would be doing this without Kyou's blessing, though, since they are (or were) all Kyou's goons. I reckon this would then make this one of Kyou's experiments. Probably an early one. Anna might be what she is due to Kyou messing with her mental development.