This is just my opinion so please don’t take this wrongly. But what if his actions are due to the way he was brought up? If you remember the chapters, Kyouji was literally violently abused by this father. In my opinion, I think that Kyouji most likely didn’t get the love or care from his parents that he needed thus giving him a more violent temperment.
Just because he had a rocky past is no excuse for him to hurt other people.
Also we have to think about it form his perspective. Hes a stressed college student that woke up to a HOME INTRUDER. Imagine waking up to a random guy in your house who doesn’t speak the language so u can’t talk creating the possibility of a scam, he doesn’t know what a shower or a fridge is which is suspicious as hell, first time u leave him alone he breaks ur TV, and then u catch him trying to pay someone with leaves. All said and done no matter how much of a pet he acts like, Nagi looks very human that’s old enough to take care of himself. Just because he let him stay doesn’t mean he automatically became responsible for all of his needs and wants. Yes I think it would be great where they get to a point where they can talk more as equals but I think that he’s better than most for trusting him to this extent and only scolding him like this Mx Most people would have just handed him to the police.
I CAN'T STAND KYOUJI! He's so annoying. Why does he have to be so mean and shout so much at the innocent fluffball. Like wtf man. He's adorable and doesn't deserve this treatment! It breaks my heart :'(