I absolutely love this anime. Watched it for the first time, all in one sitting, a couple weeks ago, because I have no life. I've heard people say there's a romantic thing going on between Rachel (under age) and Zack (not under age), but there's obviously not, you can grasp that if you're not dense. Much more of a really caring vibe, in a very dark way, wouldn't necessarily say family-like, but still. No romance.
***SPOILER AHEAD***
Only thing I wish is that it would have shown if she actually got killed or not. I'll never know and will probably think about it for the rest of my life. Hahaha. Amazing anime. I just watched through it again over the last few days.