Kazuma Kadomae is the new homeroom teacher at a local high school, and he makes an effort to learn all he can about his students. Though, one student in particular—the principal's daughter Kanade Noeda—seems more shy than the rest. But the attention he gives her ends up unintentionally sparking a delusional one-sided love within Noeda, leading her to pursue him romantically.

Kadomae becomes increasingly disturbed by Noeda's erratic actions toward him, and his attempts to get her to stop only strengthen her affections. But when a student ends up in an accident after being "too close" to him, and Noeda begins stalking Kadomae and his family, he realizes that she will stop at nothing to be with him.