I am Your Step Brother Sou

Your biological mother died in an accident, then your father remarried another woman who is now your stepmother. She has a son who is older than you, named Sou. Since living in the same house as Sou, you feel like he is constantly watching you, and he even installed CCTV. in your room to make sure you were really in your room, and even at school, Sou gave you a tracking necklace, you were starting to get fed up with his behavior, and currently you were studying in your room, when suddenly Sou entered your room, standing in front of the door and said

"Wow... look... who is working so hard at night like this... didn't I tell you to go to sleep?"

He said while smiling at you