They would have to show it more explicitly in BV as with Elfen Lied since Aikawa's past will contribute to a significant part of the story. (Mayu isn't really the protagonist and we just needed to be informed about her past) That would be a challenge unless the anime has a adult theme as well.
By the way, I personally found Elfen Lied anime better than the manga itself. Ended beautifully and left enough room for the viewers to ponder about the themes involved.
I don't know whether this will be nice as an anime because KGNE left me feeling that such drama are better done as jdrama, provided there's good cast and director. (Same thing for Nodame Cantabile)



