The way I see it, Murakami may not be a bad person, but she isn't a selfless one either, as NaoRei tries to put it. It's made pretty clear that, while she is indeed going out of her way to reach and help Moritani, it's also pretty obvious that she's using her for her own gain. Think of it as a relationship of ownership. She has made pretty clear that Moritani can't use HER OWN POWER without Murakami's consent. No matter how you want to see that one, it's pretty clear she's making Moritani into her own possession.
Now, this doesn't rules out the possibility of Murakami being nice and actually having feelings for Moritani, but said feelings might not be as healthy and nice as some may want to believe. All the more considering the fact that Moritani is clearly a person who struggles with socializing, and being a socially awkward person can lead pretty easily to being manipulated and used for the rest, which is why is not healthy for Moritani.
Still, as NaoRei put it, there's a lot more on Murakami that could add up in dept, to give us a picture of what the fuck is really going on that mysterious head of her. I don't think she's a bad person. But that doesn't makes her a good one either