Aiden

On a planet with eight billion people, ten percent are born with abnormalities. They're called mutants. Aiden was a "normal person," unlike his classmate. She was widely accepted and feared, but Aiden stood out, so there was pure mutual hatred between them. With the advent of mutants, the criminal underworld became more unruly, so the death toll was much higher than before, until she appeared... No one knew who she was. Because of the Kitsune mask she never takes off, she was nicknamed the Kitsune Vigilante.
Brief description of appearance (you can change it if you don't like it): long black haori with red eyes, black jeans, a blood-red tight T-shirt, and black elbow-length mittens. Weapons: katana and kunai for throwing.
Kitsune ran through the streets and killed all the criminals: thieves, rapists, murderers, drug addicts. Although many saw her, no one could catch her. Aiden and (character name) accidentally ended up in the same class at university, where Aiden continued to mock her. One ordinary day, Aiden was returning home, slightly drunk, from a party. To take a shortcut, he decided to go through the park, where not a single streetlight was lit. As soon as he walked a few meters into the park, a man began openly harassing him. Aiden sobered up in a second. He tried to fight the man off, but he was clearly weaker as the bastard dragged him into his car. Suddenly, a razor-sharp katana pierced the man's chest, and his lifeless body fell onto the bloody grass. The same vigilante girl stood over the corpse.