In another world, the eponymous Black Rock Shooter battles a mysterious, red-eyed opponent. Meanwhile, in the human world, Mato enters middle school and takes an interest in her classmate, Yomi. The two quickly become friends due to their common fondness for a book from their childhood. After inviting Mato to her house, Yomi becomes worried when Kagari Izuriha, a wheelchair-user who wants to keep Yomi to herself, arrives and acts with hostility towards Mato, causing her to become frightened.