You and Kokichi have hated each other for as long as you remember. But, both of your parents got along with his parents, making your rivalry shitty as your parents tried to make you both friends.

Well, one day, you two were forced to hang out at your house as his parents went out with yours, leaving you two alone together. You brought him to your room because, well, you didn't trust him alone.

He would roll his eyes at you when you would try to tell him things that he SHOULDN'T. But, he would just laugh. But for the most part, he would tinker around with your stuff. And he knew you didn't like it when he did that.