Yoru's eyes are so... cold and indifferent at times. It feels like she'd throw you away once she's done with what she wanted from you
I think I get Kuro's deal. She was helpless in her situation back then, and she's helpless at her job/public life now. But she has so much power over Aya, and from that gains so much power over Haruki too. It must feel really satisfying for her, to finally get her way, and look down on Haruki, who's in a similar position as she once was.
I'm not sure how she truly feels about Aya, but by being "honest" with her about being Yoru's replacement, she is in fact also putting her in a similar position as her teenage self: "This isn't what I really want, but I'm okay with it." Actually it might fit in pretty well with what Aya wants, she just doesn't acknowledge it. Aya's trading physical intimacy against 'friendship' after all, because she wants to be close to someone. Even if she doesn't state it (I don't remember actually), she enjoyed how it felt, when they were first texting each other, having someone care about her. Kuro is pretty much treating her like a girlfriend right now, and even if it isn't explicitly what Aya is looking for, that sense of closeness and intimacy she wants still comes along with it.
Idk how much she really likes Aya, but she definitely manipulates her hard huh. On one hand she tells her that if she won't do it, she'll just find someone else (you are disposable), but she also makes her feel like she needs her, and that she wants to keep her around. She makes a lot of gestures that outside of their context are actually very affectionate and often gives Aya words of affirmation (that she likes her, cares about her, is happy to see her, etc), but I don't know to what extent she might mean them, if they're just tactics to make Aya feel wanted, to give her a place to belong.
I'm not surprised Kuro didn't think Aya would have a "best friend", because she wouldn't have reached out online and maintained such an alarming relationship if she didn't feel lonely or isolated. Aya is such a vulnerable target with her low self esteem and lack of social support that it's no wonder that it doesn't sound like she would have such a uh concerned friend.
Anyway, uh, Kuro is taunting tf out of Haruki, and deeply enjoying rubbing it in her face. Rather than being ntr'd, she's the one netoraring someone else for once.
