Cool = Chuuni. I don't think they're speaking the same language.
Yeah, great work, teach. How to create a mafia 101.
Middle school Medusa.
Honestly, since she's not there to block him like the standard obstacle best friend, but to make sure he's a decent enough person, and she does so by actually talking with him, I think she's doing good there.
Tsundere without actually liking him. Probably. Hopefully. Suits her. But it's kind of obvious who she's doing it for, and it isn't him.
I still like her better than FMC.