My Teacher Lives here? A K.N.J fanfic

Part 1

"Hey faster and buy me food. Am hungry" That's your sister. For your infomation, it's only you and your sister living together. Your sister always hurt you if you don't follow her instructions. No one at school knows about this, even the teachers and students too. But they don't even care the students bully you, wothout the teachers knowing. You have been living like this for 4 years. One day, when you are at home with your sister, someone knocks on the door. "Hey! Go and open the door, i think it's the person who's gonna stay here." So you obey your sister and open the door. To your surprise, it is your new teacher, who you just met this morning. What was his name? Namjoon? Wait I think it's Mr Namjoon Kim. Your mouth open wide. Okay.. so he is the one who will be staying here? But he gives the face when he usually looks at people. Like the cannot be bothered face? I don't know. Anyways, before you can open your mouth and talk, your sister push you to the door and you fell backwards, your feet slid against the door gap between the door and the floor. His expression only then change to a surprise one. Your sister if she sees a cute or a handsome guy, she will push you out of the way or will forget that you are there. But for your info, she has a boyfriend and you do not have one. She also doesn't know that he is your teacher. Then she gives you the angry look to faster get up from the floor, so that it doesn't look like she push you, but like by accident. You stand up and go to your room. On the way to your room, he saw your leg that has been bleeding while you walk, on the floor but he just look from a far, because he saw how your sister looks at you.