Gee sensei. If you're starting to like him, then like him seriously. Don't tease him too much. He's just a tsundere young boy, don't play around with his heart.😅
At least her reaction is the correct one. "What the fuck, aww hell naw." She was 100% the same kind of kid that Nagai is, and it seems she totally did not intend to have any complications involving him when she was helping him come out of his shell.