Kaede Komura is in love. After being seated next to the airheaded Ai Mie for the past three days, Komura cannot help but be attracted to his bespectacled classmate. Although he has yet to have a proper conversation with Mie, Komura dreams of the day when she will look his way. One day, Komura notices that his seatmate is not wearing her glasses, learning by questioning Mie that she forgot them and has a tendency of doing so. When he sees her struggle, a concerned Komura takes it upon himself to help his crush. As the boy offers his assistance to Mie day by day, her reasons for constantly losing her glasses slowly evolve from the answer she initially gave.

Ayakashi are strange, supernatural creatures invisible to the majority of people. Though most are harmless, some ayakashi attack humans to devour their life force. Exorcist ninjas are tasked with protecting people from these spiteful spirits. Matsuri Kazamaki is a young exorcist ninja born to a prestigious clan. His childhood friend, Suzu Kanade, is an ayakashi medium—an individual with immense vitality that attracts ayakashi. Matsuri deems all ayakashi threatening and wishes to keep Suzu as far from them as possible, but this clashes with her desire to remain close to them. One day, the pair encounters Shirogane, the "King of Ayakashi," who is hellbent on consuming Suzu. As she is about to be eaten, Matsuri comes to the rescue and manages to seal the ayakashi's powers—but not before Shirogane takes revenge by turning him into a girl! Until he finds a way to transform back, Matsuri must adjust to his new, peculiar lifestyle while fighting against hostile ayakashi. Moreover, Suzu is now conflicted about her feelings toward Matsuri—further plunging their relationship into a state of ambiguity.

-ADVERTISEMENT- The year is 2242. Humanity was forced to seek refuge deep underground due to the unprecedented calamity known as the "Tears of the New Moon," but following the collapse of the underground city-state of "Amasia," they begun to venture back towards the surface with hope of living there once more. Forming settlements called "Nests" scattered across the surface, adventurers known as "Drifters" continues to battle the lingering threat of the "Enders" and mine the "AO Crystals" which are an essential energy resource necessary for the operation of the nests. In the nest "Rock Town" where such Drifters gather, one wishing to become such a Drifter one day, "Kanata," alongside the skilled Drifter "Tokio," went to explore the ruins of an old museum where Kanata happens to discover a very beautiful sleeping "Magus." With the encounter of the mysterious Magus "Noir," a tale of destiny is slowly beginning to unfold.

Fourth season of .