Maybe it's just me but this really reminds me of Sacchi's manga from "Manga no Tsukurikata," which unfortunately isn't very reputable around here, but nonetheless still one of my top favorites. As for this series, social anxiety is a serious issue that some people struggle with (myself included), but I'm glad that it could be illustrated in such a light-hearted manga. Even though that might understate the reality of it, the message is conveyed pretty well, if Bocchi wants to make friends she'll have to open up and initiate, and there has to be effort on both sides despite some thinking that friendship comes intrinsically.
I also like the little details like the brash classmate/newfound friend of Bocchi having to sound like a completely different person on texts and overuse of emoticons, the awkward tension when the other person is on their phone, etc
I think this is part of the "overthinking girl" genre. Alongside not only Watamote, but also Morita-san wa Mukuchi. And even Watamote has a Yuu-ri element. This is the only one of the three where the social anxiety and overthinking are actually realized by people around the girl, though. Good for Nako actually spelling it out, and good for Kai for confronting Bocchi about it.