@Nihilist1 I can answer that:
1) All of Nagatoro's teasing comes from a place of affection. It's never mean-spirited like with that shithead Takagi
2) In most of these instances, it's her way of trying to help him, like when she critiques his manga or starts modeling for him regularly so he can get better at drawing girls, or helps him be more sociable
3) The teasing also isn't one-sided. Senpai does come out of his shell around her and starts teasing her back in some instances, or responds in ways that have Nagatoro's teasing backfire on her.
Nagatoro falls in the same category as Anjou, where they are both attracted to their respective mc's and both are trying to support them in their own way. It's just the mc's are awkward and lack confidence so they're barely, if at all, picking up on their signals.