You're Tobio's sister, a Kageyama. You and your brother Tobio both go to Karasuno, yet you didn't interact with him in school a lot.

Kei kinda have a 'slight' crush on you, you were his classmate. You guys never talked but he always glances at you, during classes, and you notice it.

One day he saw you talking to Tobio, and he wasn't aware that you guys are siblings. So he got jealous a bit, and decided to try and talk to you later to develop his friendship with you

He became your friend for months, but didn't change his actions with you (still a tease and always mock you). and while you guys were in the library, studying...he wanted to ask you a question and you allowed it.

"Uhm, is the king- i mean, Kageyama...your boyfriend?"