@thanghe
Well it's not wrong, or better IT IS WRONG, and in a sense is what it makes this series charming.
She's in her essence, a demon, or more likely an alien being.
Her motives, her objectives, and even her way of finding something interesting are entirely different from our perception.
I think the author conveys this in a really interesting fashion.
Such small things, actions that we perceive as strange or wrong, for her are actually extremely satisfying.
For a normal human, for example, earning money means not having to worry for food and shelter.
But for a being which is not moved by the concept of hunger or time, the simple knowing that she's pissing of the Black goat with a hundred child, by interrupting her fun with her protegé might be more than worthy of all these actions.
After all, how can a simple human understand something that exists on a different dimension, in which our greatest fears and dangers, are nothing more than afterthoughts?