Gotta say... this show sucks
It seems like it was made by some perverse teenage boy. It presents an interesting idea with the telekinetic race, but that's overshadowed by unnecessary nudity, ridiculous relationships between the kids, and pretty bad dialogue.
Lucy is a sadistic killer that the show tries to make you feel sorry for. Aside from killing the people that held her captive, she killed kids at the orphanage and random people on the street. If some dude that was bullied shot up a school then slipped on the stairs on his way out, hit his head, and became retarded you wouldn't just absolve all of his crimes.
Terrible dialogue: "Do you ever think about fondling my breasts?" or "Am I really going to die on this floor as a virgin?" There's plenty more, but those were the worst lines off of the top of my head.
The way all the female characters act is ridiculous. It's that weird anime "I can't express my feelings so I'm gonna yell at you and run away" type of crap with every female character.
I watched this because everyone says it's super dark and gory. The gore isn't any different than any medieval/samurai anime with blood and hacked off limbs. I don't really know what I was expecting, I mean it is a drawn cartoon. Mayu's backstory was the only thing that was really dark, but that was one episode. Being bullied as a child and having lost a family at a young age is in Naruto, so I really don't see why people praise this as being super dark so often.