Yandere!girl x Male! reader

Monday

After (c/n) told you to meet them at the roof on Friday, you wanted it to be Thursday already "MISTER (L/N)?!"  "how what??" you spin your head around to see an upset teacher "Now (y/n) that your down spacing out I assume you know what to do next?" the teacher says "Well...um..." But you could answer the bell rang for your next class '*sigh* oh my glob talk about saved by the bell'. You race out of the classroom to head to your next class but before you could your friend stops you "Hey (y/n) you go plans for Friday?" (f/n) said with happiness "Actually I do this time" "But..But your gonna miss our anime marathon" "Sorry (f/n) maybe this Saturday?" "O-oh y-yeah sure this Saturday...Seems good enough" 'I hope she is not too upset?' 

~time skip~

Once your finished your conversation with (f/n) you felt something was off with (f/n) and that they were upset about you having plans with someone 'Maybe (f/n) really wanted to hangout with me that bad?'. It's didn't effect you a whole lot because you were too excited to see (c/n) on Friday "WHY IS FRIDAY SO FAR AWAY?!"  you thought you said inside your head but really out loud...luckily no one heard you, you head to your locker to see a pink piece of paper taped to your locker 'what is this?'. You pick you the letter and open it and it said:

Hello (y/n) 

You don't know who am I and you never will,I heard you little conversation with (c/n) and I won't let that happen. If I were you I'd watch your back and be careful who you talk to because there maybe a little....accident,farewell (y/n)

~unknown~

you read the letter a couple of times just to be sure 'WHAT IS GOING ON HERE,WHO IS THIS PERSON?!'

???'s p.o.v

I see (y/n) got my letter and looks really scared I didn't want to scare him,but if it means him not seeing that B**** then its what I have to do it's only Monday and I have to anything in my power to stop them from meeting.