A mysterious transfer student arriving at Gekkoukan High School uncovers an unsettling truth: each midnight, the world succumbs to the Dark Hour, a supernatural phenomenon that transforms ordinary people into coffins while reality warps into a nightmarish landscape. The school itself morphs into Tartarus, a labyrinthine tower infested with creatures known as Shadows, and the new student discovers he possesses the ability to summon a powerful manifestation called a Persona using a gun-shaped device called an Evoker. Recruited into SEES, an underground organization of fellow students dedicated to fighting these entities, he must navigate the dual challenge of maintaining a normal high school existence—attending classes, building relationships, and studying for exams—while descending into the depths of Tartarus to battle increasingly dangerous Shadows that emerge on moonlit nights. As the group pushes deeper into the tower's mysteries, they begin piecing together the dark history behind the Dark Hour itself.