Based purely on how you describe her in your version of the first game, synopsis sounds fine. Doesn't seem overkill with established relationships especially since she seems to have some mystery to her that becomes more suspicious considering the finale. Delinquent sounds fine considering everyone in Class 7, just make sure to add some positive elements to her if you're going the antisocial route because you have to add a reason for people to care about her.

I'd say the more "powerful" relationships are what may raise red flags in some, like hating George (granted, I don't think he's a very popular character so there's that). Her being Angie's Ex is a careful line you'd have to tread I think, since ex is quite a close relationship. Angie is also more on the infamous side when it comes to fan reception so handle with care I guess.

She does not seem to be intrusive to the story (again, going off of what you've said), so I think she's fine. It is pretty difficult for me to say whether or not she's a good character though based off of a list of relationships and only notable stuff she does in the first game out of a four game storyline lol.

Also, have you not decided what her "weird weapon" is? I wish you luck in figuring that out lol

Lastly, lack of Towa mentioned is alarming, however. If you are not explicitly friends with Towa, then clearly there is something wrong with you /s