Akane, a high school student, visits the detective agency from Kishibe-chou Kidan: Tanbou-hen (2012). Akane tells him that she is being followed at night by a mannequin in a sailor suit wearing a mask. An agent immediately solves her problem. However, similar phenomena occur one after another, and several people witness the masked girl in succession. Is this a prank, a misunderstanding, or a real ghost?