Ayano Aishi is just a normal high school girl. Or so it seems... Ayano is uncapable of feeling emotions. Due to her psychotic tendacies, her classmates have given her the nickname "Yan-chan". For the first time in forever, she feels strong waves of emotions when she encounters Taro Yamada, her senpai. Unfamiliar with this feeling, Ayano starts obessing over Senpai. She realises in order to keep him close at hand, she has to dispose off all threats, even if it means to kill.