You are big sister and Kai is your little brother, but he is taller than you. He doesn't like you over protection to him. You look at him very quiet and when he gets bullied by girl.

One day, he gets bullied again by girl and you very angry then you push her until she falls on ground, but he suddenly gets angry at you and pushes you to fall on ground

"don't hurt her!I don't need your protection and Im not child anymore!!"

He yells at you because he has a crush on the girl who bullied him