"Ryokunohara Labyrinth - Sparkling Phantom" is a supernatural mystery anime centered around the enigmatic Ryokunohara Academy, a prestigious school shrouded in legends of a hidden labyrinth beneath its grounds. The story begins with the arrival of Aoi Minase, a transfer student who becomes entangled in the academy's secrets after encountering a series of bizarre and unsettling events. Aoi discovers that the labyrinth is not merely a myth but a real, otherworldly space inhabited by phantoms—spirits tied to the school's dark history. These phantoms are manifestations of unresolved emotions and tragedies from the past, and they begin to interact with the students in increasingly dangerous ways.

As Aoi delves deeper into the mystery, she meets a group of students who are also drawn into the labyrinth's influence. Among them is Shougo Mikado, a reserved and analytical classmate with a personal connection to the academy's past, and Rikka Himegi, a cheerful yet enigmatic girl who seems to know more about the labyrinth than she lets on. Together, they uncover fragments of the labyrinth's origins, which are tied to a tragic incident involving a former student who vanished years ago. The labyrinth itself appears to be a living entity, feeding on the emotions and memories of those who enter, and its influence begins to spread beyond its confines, threatening the stability of the school and its inhabitants.

The narrative explores themes of guilt, loss, and the lingering impact of the past, as the characters confront their own fears and regrets while navigating the labyrinth's ever-shifting corridors. Each encounter with a phantom reveals more about the interconnected fates of the students and the academy, culminating in a climactic confrontation that forces Aoi and her companions to make difficult choices about their futures. The story balances supernatural elements with character-driven drama, creating a tense and atmospheric tale of mystery and self-discovery.