She's honestly really cute. This chapter is complete fluff so I'm not complaining.
It would be nice to see a bit of character growth though. For him, be a bit more self-confident. For her, be a bit more supportive in general (since well, he's an introvert).
I just hope this doesn't go the way I fear, and his personality just gets overwritten by Machino.
It's one thing to become more confident and willing to venture outside the walls of that clubroom, but the start of this series was Machino showing up while he played with dominoes, she'd fire off random nonsense and he'd counter her quirky jokes and schemes with his "straight man" routine, then she'd leave and he'd wax philosophical about whether the exchange held some deeper meaning to the whole concept of 'youth' and 'life' and whatever.
The last few chapters haven't been that, though. Even when we introduced Yagi and Yukide, we still had those exchange moments bewteen Nitanda and Machino, and he would "give as good as he got", as it were. There was actual balance to their dynamic by the end of each chapter.
Since chapter 7 though, that seems like it's been shelved. That chapter, it was Yukide who was in the clubroom the whole time, and when Machino
did show up, she badmouthed Nitanda for being a pervert despite clearly "misreading" the situation she found them in, not giving him a chance to explain, and then left without her customary goodbye. The next chapter, she was much more meek and reserved, and seemed to go out of her way to act the opposite of how she did previously, though without actually acknowledging her sudden shift in behavior.
This time, it's the four of them, outside the clubroom, and he's simply being lead along by Machino and the others and is largely the sort of "background character" that Yagi accuses him of being here ('you always look at these things from a distance, huh').
It's great to to see a character stepping out of their shell, but not when it comes at the cost of who they are. I don't think it's irreversible at this point, but their dynamic has shifted and it's changing Nitanda more than it is Machino, at least by all appearances over the chapters we've been given. I'd said back around chapter 3 or 4 or so, that I hope that's not what's being done here, because it's fairly standard in the "introverted ML & extroverted FL" school-age romcom titles to have the ML's personality overwhelmed and changed by the FL, like he's "wrong" for being the way he is.
So if he's going to change, I hope it's not at the expense of who he is as a person. He can become more self-conifdent, but it shouldn't cost him things like his dominoes or his joy of going at his own pace in his clubroom, whether others are there or not.
He calls this his "undeserved youth" at the end, so I guess we'll see what comes in future chapters.