Misaka and Kuroko invite Uiharu and Saten to visit them in the School Garden, private grounds normally only open to the members of various elite schools nearby, one of which, Tokiwadai, is part of. On their way to meet the two, Saten's school uniform is soaked and ends up borrowing a Tokiwadai uniform while hers dries. The cake-eating festivities are put on hold as Kuroko and Uiharu are called into work by Judgment. There they learn that there have been several attacks on Tokiwadai students which rendered them unconscious, and with large bushy eyebrows drawn on their faces. Going through the Academy City databases, the only possible suspect appears to be Miho Jufuku, who has the ability to mask her presence to the human eye.
Back in the School Garden, Saten is mistaken for a Tokiwadi student and is attacked in the washroom by an unseen assailant. After recovering, Saten confirms that the person who attacked her was Jufuku, as she saw her reflection in the mirror.
The girls go on the hunt for Jufuku, with Uiharu coordinating them in the Judgment offices utilizing the network of security cameras on campus. After capturing her, the girls learn that Jufuku was on her crusade against Tokiwadai students because her boyfriend dumped her for a Tokiwadai student.