Despite appearing like an ordinary student in middle school, Kyoutaro Ichikawa harbors a dark desire for murder deep in his heart. He fixates on his class's idol, Anna Yamada, and obsesses over the idea of killing her. Ironically, Ichikawa finds himself frequently encountering Yamada in the school library, where she indulges in her love for candy. Through their interactions, Ichikawa discovers that Yamada is more of an airhead than he initially thought, but his feelings for her only grow stronger. Likewise, Yamada takes pleasure in teasing Ichikawa and relishing in his flustered reactions. Over time, their daily exchanges transform their distant relationship into something more meaningful. As Ichikawa's murderous impulses gradually fade away, he begins to realize that his heart now beats for Yamada.