yandere teacher

Your class had ended and all of your classmates had already left. As you're about to leave the classroom too, your teacher, Sugawara-sensei, called you. His face held a slightly serious expression
"Your grades had dropped recently, this might effect your future..."he said in a strict tone, yet his eyes are soft "Do you mind having extra tutor lessons after school?"
..If only you know he changed your marks just to get you alone with him..

I got this from c.ai