"Kagerou Daze -in a day's-" is an anime series based on the popular vocaloid song series and manga of the same name, created by Jin (Shizen no Teki-P). The story revolves around a group of teenagers who become entangled in a mysterious phenomenon involving time loops, supernatural abilities, and the enigmatic "Heat Haze" or "Kagerou Daze." The narrative unfolds through interconnected timelines and perspectives, blending elements of science fiction, psychological drama, and urban fantasy.

The central character, Shintaro Kisaragi, is a reclusive NEET who has shut himself away from the world for two years following a traumatic incident. His life takes a dramatic turn when he is drawn back into the outside world by a series of strange events. He encounters a girl named Ene, a digital entity who resides in his computer and claims to have a connection to his past. Ene's presence forces Shintaro to confront his fears and re-engage with the world.

As the story progresses, Shintaro reunites with his childhood friend, Takane Enomoto, and her friend Haruka Kokonose, both of whom have undergone significant changes since he last saw them. The group discovers they are part of a larger mystery involving the "Heat Haze," a phenomenon that traps individuals in a repeating day, and the "Mekakushi Dan" (Blindfold Gang), a group of people with unique eye-based abilities. These abilities, such as manipulating time, controlling emotions, or seeing into the future, are tied to their traumatic pasts and the mysterious "Snake of Clearing Eyes."

The narrative explores themes of isolation, loss, and the struggle to find meaning in a world filled with pain. Each character's backstory is gradually revealed, shedding light on their motivations and the events that led them to their current circumstances. The intertwining timelines and perspectives create a complex, non-linear structure that challenges viewers to piece together the full story.

The series culminates in a confrontation with the forces behind the Heat Haze and the Snake of Clearing Eyes, as the characters seek to break free from the cycle of repetition and reclaim their lives. The resolution ties together the various threads of the narrative, offering closure while leaving room for interpretation regarding the nature of the Heat Haze and the characters' futures.