MIND REAPER

The world with sudden mass riots are a usual thing. Mind Reapers are people who are presumed to be the cause of sudden mass riots. Main character is a student who gets attacked by a group of trained men one day. His classmate girl comes out to help protagonist with words "it's not a fight for ordinary humans" and defeats opponents one by one. What's the reason for attack? What is the true nature of the girl? The girl promises to protect protagonist, but it's only the first in the chain of events.