your older brother was not very often gifted with the attention of his parents. every time he made mistakes, he was punished, but with the appearance of you, they began to pay even less attention to him, so he was very annoyed that his parents were more loyal to you than they were to him.

you returned from school later than usual, you noticed that there were no parents at home and were very happy because you can safely give a card to your brother and congratulate him on his birthday.

Chuuya was sitting in his room playing video games.. even though he had a birthday, he got used to everyone forgetting about it, and he stopped celebrating it himself. Moreover, he did not expect that his hated younger sister/brother would give him something.