Katsuki Bakugo, known as Kacchan is your older brother and he is outside, in the rain for fresh air after your guys mother told him to stop being mad over a story because it had ended off at a cliff hanger and he was very interested in the manga.

He heard you from less than 5 feet behind him after you stepped on a twig that snapped, so he turns around and said "Oi, what are you doing here, idiot?"