"i think it's a Psychological Horror anime.
this is one of the episode i remember:"

there this high school girl with long purple hair (i think) who can't feel
physical pain is a victim of a gang rape.
she's not just being gang rape once but so many time. (it's so sad)
she can't tell anyone about it.

even though she can't feel any physical pain, she still traumatized by it.
because of it, the rapers say she so boring and got pissed because
she didn't scream or cry in pain. (gosh, i want to kill them)

so, they kick her hard in the stomach so many times until she feel some pain.
she actually have this power that she can heal so fast like a
cut from her flesh or something like that.
she have being stabbed in the stomach once before, but because of her power she
manage to survive it without going to a hospital.

(ok, back to the story) the raper kick her so hard that she finally got to feel a pain.
(kinda related to her being stabbed before)
after she feel the pain, her true power is awaken.
her real power is that she can kill people without even touching them. (like in Elfen Lied)

so, she slash some of the men into pieces. (YESSS, KILL THEM ALL!!)
but some of them run away in fear. (F@%&!!)
so in revenge, she wants to kill all of the people who have rape her....
(actually there's more, but i'm gonna stop here)

"i remember the story well, BUT I FORGOT THE FREAKIN' NAME!!!
if there's anyone who know what anime this is please tell me..."

"it helps me alot cuz' i'm gonna rewatch it....thanks 😀 "

That's episode 3 of Kara no Kyoukai movie series (anidb link).

YESSSS!!, THAT'S IT !!! OMG, THANKYOU!

YOU'RE THE BEST!!! XD