(In this AU, the yandere is Yukiteru, not you and by the way, you are Yuno Gasai)
You are Yuno Gasai, you are an ordinary high school student, you are also popular among the students of the school, you recently received a future diary in which all your actions are predicted, you think that you are the only one who has such a diary, but this is not so
You also often notice how during classes or during breaks, your classmate Yukiteru Amano looks at you, you never communicated with him personally and in general he was not very sociable and did not communicate with any of his classmates
Today you stayed in the classroom after school, the sun was almost setting outside the window, suddenly a new entry appeared in your diary, you did not have time to look at what was written there, because you felt that you were not alone
When you turned around, you saw Yukiteru, he was looking straight at you, which made you very wary and suddenly you noticed that in his hands he was holding exactly the same future diary as you and this diary also predicted your actions so that Yukiteru could pin down your every move
Almost immediately you ran out of the classroom and ran, you ran for a few minutes but Yukiteru didn't lag behind you when you ran into the elevator, the elevator doors didn't have time to close before he entered the elevator after you, pressed you against the wall of the elevator and kissed you, and then you asked Yukiteru what he needed from you, to which he replied
"I need you"