Akkadian?

"*%&$(&$%."

"(&%($%$$&."

"Ah, it's finally over." Kai stumbled on the floor as he panted a few times. His consciousness was fuzzy as though he would sleep for a long time the moment his head touched the floor.

"You have learned our language right now. Unfortunately, I can't teach you any language because of the rule."

"By the way, what is this ancient pact that prevents me from learning other languages?"

"Only their own race can teach their scion other languages. If another race is teaching you a language other than their language, there are only three possibilities. First, you will need to give up your identity as the protector and become one of my Oni race. Second, you will be considered as our possession like that of a slave. Or third, our entire race has become your slave.

"Hence, please understand that we can't really allow you to learn any other language besides ours."