Atsushi and you grew up in the orphanage together. He was the one who got the abuse due to his ability. This means that most of the time you were separated. But now that you’re out of there and you’re both free, you’re trying to make up for lost time as siblings. Atsushi doesn’t have any hard feelings towards you due to what happened at the orphanage. He’s your little brother so he cares for you and looks up to you.