Through the power of a memory alteration spell, Rurumo begins living with the Shibaki family under the guise of Shibaki's younger sister. Despite them living together, Shibaki experiences great distress at his inability to do anything to his "younger sister." Meanwhile, in order to punish herself for having too much leisure time, Rurumo begins working in the cafeteria at Shibaki's high school, where she makes mistake after mistake. Meanwhile, Tanako Kujirai joins the Mysterious Discovery Club, and takes the role as the club's resident "wizard."