Nagatoro is so predictable in the way she got nervous at the thought of someone else giving him chocolate or even being interested in him. But in a way, it kind of is nice how this mangaka built a character with a simple role set. In that, she is a girl in love with this guy and loves picking on him like a grade schooler. The roles are reversed in the sense normally a boy would act like a brat to get the attention of the one he loves.