Well this series is great or maybe my taste is getting worse. Naoi's improv skills are pretty amazing though.
We see Kokoro is idolizing her a bit and a normal response would be for Kurumi to try to live up to Kokoro's expectations, thereby becoming a better person in the process and feeling like there's some value in 'being' the kind of person Kokoro likes and supports (since there's at least one person for whom it's worth it), while Kokoro gets a more realistic understanding of Kurumi over time and forgives Yoshizawa for considering stealing (considering Yoshizawa didn't actually steal it). A lot of people were predicting Kokoro being evil, but it seems like she is really just going to be a nice person who wants to support Kurumi.
Instead of that dynamic where their relationship is deepened, we somehow go straight to Naoi disproving that Yoshizawa is not the type of person who would hurt someone. Naoi would have had no idea what would be the result of sending the video, come to school anyway, and then basically followed them around while trying to come up with a way to get the result she wanted. It's quite unhinged behavior, but she also seems brilliant in her social engineering skills, like the kind of person who becomes a CEO or founds a new religion.
A lot of the misunderstanding really stems a lot from Kurumi not communicating to Kokoro that there was more to the situation or considering why Kokoro might be uncomfortable being put in the position of "the only person who knows." Kokoro wanting to involve an authority figure is relatively reasonable and "I don't want to worry my parents" could be a statement made by someone downplaying the impact on themselves, rather than someone who doesn't have the type of relationship with their parents where they can talk about stuff. Kokoro presumably does have that type of trusting relationship with her parents.
This kind of gap in understanding is actually pretty realistic I think, where often well intentioned people make things worse for kids in abusive or difficult home environments and do so in a way where the person in the bad situation ends up blaming themselves. Probably the situation will deteriorate a lot more as Kurumi goes past the point of what Kokoro can accept or forgive.
I also want to say that the author is also really good at the panels of Naoi grabbing Kurumi, like
page 21 in this chapter or
page 8 and
page 9 in chapter 4. We get at least one of these pretty much every chapter. The dynamic is different even when Naoi gets Kurumi to hit her, as even then Naoi is smiling and seems in control, whereas we get these nice overwhelmed/disoriented or scared expressions from Kurumi most of the time, much like on the cover art for the series. I legit spend the month looking forward to getting to see more of these. This really started with
the writhe around like a bug panel in chapter 1, where Naoi seemed surprised at Kurumi's reaction, but since then appears to have been seeing what reactions she can get out of Kurumi by acting this way with her. That would make sense, given that she would be in jail if she was like this with everyone.