So basically this is a revenge story, where the black-haired girl (the MC) is getting revenge on a magical girl who murdered her best friend (the blond pixie cut) girl in cold blood. If there’s a part 2 of this manga please do so. So basically the black hair girl is avenging her best friend by going after the magical girl who killed her.
To be honest, i do understand the magic girl. She's forced to play a super happy girl to give people hope, understand that in war there are casualties and she does her job well. It looks like other magic girls cause more problems than her. In a world were negativity can create real monsters, it makes sense that the media is heavily monitored. The writer had to make her push the mc just so she actually looks like a villain.
Honestly the pure girl seems like any regular girl thrust into that position, would act. She didn't want to become a hero but has too, and copes the best she can. She really doesn't look like a villain to me, like she was right, she was defending a whole city and a innocent life taken mid battle is just a unfortunate but what can you do? Not fight a monster in middle of city?