Hanayo, who believes she has encountered her own doppelganger. She becomes frightened after seeing someone who looks exactly like her, and the situation becomes even more confusing when it seems connected to her mother and younger sister. Because of this, rumors about a supernatural “double” start spreading. Kanna looks into the case and asks Chuzenji-sensei about it, and he begins analyzing the situation to explain the logical reason behind the supposed doppelganger.