A person on mars though doesn't suddenly go from being a little girl, to being a young adult instantly(also pretty sure humans on Mars would continue to use the Earth calendar).
Yeah, she physically ages instantly, because magic. But did she also mentally age instantly? Or is that just the way a little kid that's suffered the kind of horrifying trauma that she has acts?
Personally, I'd be uncomfortable lusting after someone that was a little girl last week because some magic nonsense is giving me the green light.
It doesn't help that she's his slave. I realize she willingly requested to become his slave again, and the anime tries to pass that off as sweet, but in reality that would be a huge red flag that she's suffering from some serious mental issues.
MFauli actually mentioned earlier in the thread about what a Black person would think about that scene, and I agree with him.
"Well, I was freed from my slave master, but they were actually pretty nice to me. So as a symbolic gesture, I'd like you to put my shackles back on and give me a few lashes for old time's sake."