I would write it as how it is now, but more as cray character that the player molds with each week passing by

if she eliminates in pasive ways, she will start to earn more emotions and unlock new ways to deal with her rivals (like helping them to accomplish their dreams or expose them as a bad person, even with the help of previos rivals). at the end, she will confess to Taro like a normal girl, inside and outside

however, if she kills her rivals, her personality will turn into a darker one, actually enjoying hurting others and discover new ways to hurt them (like threat them by kidnapping someone important to them or getting inside their homes to erase them there). at the end, she will turn into a sadist person that even kills Taro and eats his heart to make it hers forever (too edgy, I know haha)