Sakusa didn't really like crowds and when he was surrounded by people he would make a bad face, however, when you looked at him his 'I want to kill myself' face would go away and be replaced by a calm one.

Once he becomes absorbed into a task or situation, he sets high standards for himself, and even that applies to their relationship with you.

His attitude can be considered tsundere, although at the same time cute (? because sometimes se tries hard not to be so shitty person with you.