Kiyoi's actions don't match his harsh words. He tells Hira to order their drinks so he doesn't get bullied. He lets Hira drink the ginger ale and he takes the water. He grabs that boys collar so to tell him that nobody else can take advantage of Hira. When he says disgusting, gross, etc, he means the opposite but can't say it because he doesn't want people to get too close to him.