She gets a redemption arc in the back half of the chapter, but having not played the game myself (I just read the character profiles on TV Tropes), I don't know whether she truly gets over her anti-Gehenna bias or merely decides that her relationships with Nagisa, Seia, and Sensei are more important.
Neither. She's far from the only Trinity student to despise Gehenna to the point of welcoming all-out war with them. It's a fairly popular sentiment, as well as mutual.
More Volume 3 Spoilers
Her redemption begins with the revelation that everything she did was the machinations of an abusive, manipulative adult, resulting in a rapidly declining mental state and increasingly poor decisions as her life spiraled out of control. Her arc culminates in a self-sacrificing stand against the Saint Justina Mimesis horde while Sensei deals with Maestro and his Hieronymus Mimesis.
What really seals the deal on her redemption is the epilogue, in which she, unlike a certain someone, faces severe consequences for her actions. She narrowly escapes being expelled, loses her position in the Tea Party (Trinity's ruling party) and all the perks that come with it, is transferred to a "common student" dorm that treats her like a convicted criminal (I mean, she kind of is), and is relentlessly bullied by the entire student body while the school's staff are as useless as real life school staff.
Compared to Rio (until she gets a proper redemption), she's extremely sympathetic and it's hard not to support her.
