Idk, it doesn’t sound like teasing to me. A constant feed of judgemental remarks will make you dislike, if not hate, someone. They didn’t really seem like quips, especially if you follow it up with “what? don’t you have anything to say?” when you notice the other person isn’t laughing and actually looks quite angry. That’s bully behaviour. If my brothers did that, I’d hate them too.

Makio’s sister may have loved Makio, but if that’s how she’s showing it, then it doesn’t matter.