I think Miko has both potential and potential to be annoying. But for now, the results being close at all is only thing i'm strongly against. It made no sense.
That bracelet feels like the kind of thing that a Light Novel would spend all too much text on explaining the significance of. Here it can only be inferred from their conversation that it is like giving her a ring without a proposal. It is not explicitly an engagement, but both are aware it...
So last chapter was Kashiwagi getting upgraded in relevance, with new character traits to go with it. And then this chapter codifies her relation to the main duo and the type of joke she will be used for.
I'm pretty sure the 3 IQ is just Kaguya's impression. If you pay attention to it, while Chika is constantly portrayed as a massive airhead, when it comes to actual knowledge, she is always on point. Like at the end of this chapter, she identified the type of cockroach even faster than Kaguya. Or...
Ultra sheltered girl just got a 16 minute sex ed crash course, from Chika of all people! And Chika looked like she had fun with it once she got over the initial embarrassment 😂