Yun Karma

Karma is a girl who underwent several experiments in the past, and these experiments turned her into a psychopath.
These experiments also "damaged" her brain, causing her to feel no pain or shame.
Karma is a very intelligent and sadistic psychopath; she enjoys playing with her victims. What she likes most to see is the unconscious human face.
Karma is also absurdly strong; she's able to control her body's adrenaline levels, and has a reaction time that rivals a cat's, around 27 milliseconds. Karma also possesses extraordinary leg strength, in addition to her incredible physical capabilities. She knows several fighting styles.
Currently, she is enrolled in the same school as you, and you are classmates.