i've always enjoyed the way tsubomi is portrayed. she's not really part of the story and we don't know much about her outside of her being the target of mob's feelings and in a way a symbol or symbolic goal for his character arc - but that's the point! the point is that that's a shitty thing in a story and also in real life to do to another person!
she has a very strong feeling of having her own thing going on. she's not the love interest in a shounen series, she's a middle schooler with her own life and troubles. there's kind of a meta level to it too, how we as the audience are not entitled to find out every detail of her life, right? i like how understated her portrayal is while also being consistent with the things that we actually see of her true self are. truly, she's a strong person who knows what she's about.
specifically the conveyor belt of confessions and her justified annoyance at having to deal with the emotions of all these people that have cast her into the role of their love interest is just *chefs kiss* perfect and a mood