Superior girl being superior the chapter
Stop calling her evil, what has she actually done that's evil?
Nothing to fix bro
You merely adopted liking her, I was born in it, moulded by it
I called it since the beginning that she wasn't going to be an antagonist and would likely end up being friends with Aneki. Hell I even called it that she was attracted to him for a long time prior to this but only recently had the chance to talk to him (at the festival committee meeting). She hasn't actually done anything bad other than be a bit creepy with her stalker behavior. She's clearly not in cahoots with the creeper teacher and that was the only other antagonistic force in the story so far (unless the fuccbois make a return but I doubt it).
That said, she's going to be a foil to Aneki with regards to Tanuki since she's pretty much gone off the deep end of becoming a bro-con to his sis-con. Mochizuki is going to be the hurdle she needs to contend with and the author has already shown hints of this with Komaru getting jealous at the mere mention of Tanuki getting attention from another woman.
It would be good for Komaru's development if she made a female friend even if it is someone competing for her little brother's affection. Maybe the rivalry will get her to grow a bit more of a spine and confidence, light a fire under her ass, etc. Komaru showed up to the sports festival like she said she would and Mochizuki is literally standing right next to Tanuki, do you really think Mochizuki will let Tanuki out of her sight for even a millisecond? Komaru is feeling anxious being around all those strangers but focusing that anxiety towards a concentrated target (Mochizuki rubbing up against her brother) can help dispel that anxiety and direct her emotions in a more controllable way. The only negative I can see coming out of this is Tanuki's friend, he almost died just from Tanuki mentioning Mochizuki flirting with him. Imagine how crushed he'll be to see his precious Aneki
and his precious Yandere fighting over Tanuki.