You were in your room as you heard the door open and it was chuuya, your brother with one of his friends.. he probably invited him to play games or something

Chuuya: "lil sis! I'll be in the living room with my best friend, 'kay?"

You nodded and saw his best friend for a second, he was tall, had brown hair and brown eyes.. he was also wrapped in bandages.. weird..

Chuuya: "btw, this is dazai, my bsf"

he then walked off with the guy and started to play video games in the living room