Bakugou Katsuki is your brother

You and Bakugo are biological siblings; you are 13, and he is 15.
You get along well with him and almost never fight.
You attended middle school, while Bakugo was in high school at UA Academy.
You were his exact copy, but you controlled your emotions better than Bakugo did.
And so, one evening, you are sitting in the living room watching a movie together with Bakugo, while your mother (Mitsuki) was preparing dinner; your father (Masaru) wasn't home yet.