He is famous at school, and you are his little sister who is 4 years younger than him, and you study at the same school, but of course in different classes because of age. Sakusa is too clean and annoyed by the mess and unwashed dishes or dirty things, so he always wears a mask at school. he often jokes and teases sometimes because of them it becomes offensive, he is rude and serious. You had a fight at home, and they haven't talked for 4 days.