Yandere!Reader x Kokichi

The "Crush"

It had been a few weeks, your brother had been talking about his new "boyfriend" for a while and honestly you kinda wanted to meet him he sounded interesting to you the way rantaro described him it was just something about this guy that peaked your interest and you didn't know what, but it was about time you got ready and went to school
"Ok rantaro I'm going out to school." You said. "Ok meet you there." Rantaro called out from upstairs
You went out and waited for the bus. When the bus finally came you got on and sat next to Kirumi of all of the 15 students Kirumi was the most bearable. She didn't bother you about wearing long sleeves in the middle of summer. Oddly there was something off you and Kirumi would count the heads and try to name the students by their hair it was fun usually there were 15 but when you counted there were 16 when you got off the bus the 16th was a small boy with purple hair but he looked new and you found him strangely adorable he felt like the missing part of your life. No one could have him. He will be yours. (That got dark real quick)
Later that day rantaro caught up to you and Kirumi in class "hey rantaro it's about time you got here" you said. He just shrugged it off and went to his desk. Weirdly enough you were sitting behind the new kid. So you just stared at the back of him blankly. After the teacher got to class he announced the new student and called him up to the front of the room "Please, introduce yourself." The purple haired boy nodded and said "hi my name is Kokichi Ouma" he gave a big smile it was so beautiful. You couldn't help but blush when he stared in your direction. Then the teacher asked the class to introduce themselves, one by one they said their names until it got to you.
You stood up awkwardly "h-hi my name is (Y/N) Amami" you said he seemed to find something about your name interesting. You sat back down and waited for him to focus his attention on the next person once he did you silently screamed in your head on how bad your first impression was. Later that day you sat with Rantaro, Kirumi and Ryoma at lunch and much to your surprise Kokichi joined you and sat at the left side of Rantaro (your sitting on the right side of rantaro). "Hi" He said "Oh hey Kokichi" Rantaro said happily. "Umm is there something up, you seem really happy" I said
"Oh I forgot! Kokichi this is my sister. (Y/N) this is my boyfriend Kokichi"
"So this is the (Y/N) you always talk about. It's nice to meet you"
You couldn't help but blush "It's nice to meet you too"
He seemed so innocent and sweet it was kind of what you expected... for a while that is. After a few minutes of lunch Kokichi went somewhere. Eventually Rantaro went looking for him they both didn't come back. Finally the bell rang. You, Kirumi and Ryoma went to class and Miu pushed passed you guys and opened the door all of a sudden water spilled all over her and a bucket fell to the ground. She ran out to dry off. Who would pull a prank like that you thought, until you walked in the door you saw rantaro looking uneasy and kokichi sitting at his desk smirking with his hands behind his head. "Nishishi (or neehee idk) that was super funny!" Kokichi said
"Rantaro why didn't you stop him?"
"Uhmmm reasons." That didn't sound like rantaro at all
"You know you're going to get in trouble"
"I know"
"And Kirumi is going to have to clean this up"
"I know"
"And Miu is now soaked"
"I know"
"Good" Kokichi said
"Kokichi stay out of it"
"You're the worst" You said as you playfully walked over and punched him in the arm "No Korekiyo is the worst." He said "yeah you're right I could've been born into a worse family" Kokichi just sat there and laughed.
Y/N's POV
the teacher came back with Miu "Whoever did this it's not funny! You will be punished!" The teacher announced. I looked at rantaro and kokichi they looked worried. So I raised my hand "I did it. I'm sorry" I said, Kokichi obviously was surprised and most likely happy he got away with it. Later after school I had to clean the school, scrape gum out from under the desks and then sit in detention for 30 minutes. After that I came home to Rantaro hanging out with Kokichi I still liked kokichi a lot and I started disliking rantaro because of their relationship but rantaro is still my brother and Kokichi seemed to be happy so I didn't want to interfere. Silently I grabbed a knife from the kitchen and brought it up to my room. I had already started cutting myself for feeling empty inside so I thought every time I start crushing on Kokichi I simply just cut myself. I cut myself a lot that day, I couldn't take it anymore I needed to do something about this, see a phycologist, maybe but I couldn't EVER bring myself to tell either of them. Things would be too complicated, ah I could move somewhere far from hopes peak but then my friends would miss me ugh I can't think of anything reasonable and the more I try the more and more Kokichi fills my thought's. I don't care anymore I'm just going to sabotage their relationship no then Rantaro would hate me if I started dating his ex, I know I'll just kill Rantaro "PERFECT!" I yelled oh no they could hear me yell that couldn't they "(Y/N) is everything ok up there?" Rantaro asked "Yeah" I said. Then I realized that my hands had moved on their own and I accidentally cut myself too deep "aw shoot" it almost bled all over the carpet luckily I managed to get to the bathroom before it started bleeding I put ace bandages on my cut up arms so that they wouldn't bleed then I realized I had blood on my shirt so I changed but I had to wear a short sleeve shirt because I'm out of long sleeve shirts. After that Kokichi left and I came downstairs I couldn't find Rantaro so I assumed he was in his room until "(Y/N)!" Uh oh, he sounds mad I went upstairs to find him holding the bloody knife
"Rantaro! It's not what you think!"
"(Y/N) you can't keep doing this because you think you can't feel emotions"
Out of pure stupidity I said "it's not that anymore though"
"Then why is it"
"B-because"