Yatsuki Nishizuru, a part-time employee in Akihabara, possesses the rare ability to perceive and interact with spirits—known as youkai—that reside in the district. Nevertheless, Yatsuki attempts to disregard them, maintaining an ordinary routine by working, caring for his younger sister Nanao, and frequenting a nearby maid cafe. Yet, Yatsuki's existence abruptly grows far more complex when an odd girl drops from a tree directly onto his face. This girl, Rokka Ayatsuji, rapidly befriends Yatsuki and Nanao, until they uncover that she is actually a Rokurokubi, a soul-devouring youkai capable of extending her neck to extraordinary lengths! Concurrently, Yatsuki discloses that his sister's physical form and spirit are distinct—Nanao is a ghost. Simultaneously, one of the cafe maids, Momo Chitoseya, becomes possessed by a malevolent spirit. Yatsuki and Rokka's exorcism of it catches the eye of Momo's sister Nagi, a professional medium, who recruits them for youkai extermination. In return for Yatsuki eliminating the more perilous youkai in Akihabara, Nagi will seek a method to restore Nanao's spirit to her body. Unable to continue ignoring the hidden world surrounding him, Yatsuki must embark on his quest and repeatedly endanger his life to save his sister's.