"Aoi Hitomi no Onna no Ko no Ohanashi" centers on a young girl named Aoi, who possesses striking blue eyes that set her apart from others in her rural village. Her unique appearance makes her the subject of curiosity and superstition among the villagers, who often regard her with a mix of fascination and unease. Aoi lives a quiet life with her grandmother, who cares for her deeply but harbors secrets about the girl’s origins and the significance of her eyes.

The narrative unfolds as Aoi begins to experience strange occurrences tied to her blue eyes. These events suggest a connection to a mysterious, otherworldly realm that exists parallel to her own. As the story progresses, Aoi encounters a boy named Haruto, who claims to have knowledge about her eyes and their true nature. Haruto reveals that Aoi’s eyes are a gateway to a hidden world inhabited by beings known as the "Watchers," who observe and influence the human world from the shadows.

Aoi’s journey becomes one of self-discovery as she learns more about her role in bridging the gap between the human and Watcher realms. Her interactions with Haruto and the Watchers reveal a deeper conflict: the Watchers are divided between those who wish to protect humanity and those who seek to exploit it. Aoi’s blue eyes, a symbol of her dual heritage, become the focal point of this struggle, as both sides vie for her allegiance.

The story explores themes of identity, belonging, and the tension between two worlds. Aoi’s relationships with her grandmother, Haruto, and the Watchers are central to the narrative, as they shape her understanding of her place in the world. The series balances moments of quiet introspection with moments of tension and action, as Aoi navigates the challenges of her unique circumstances. The resolution of the story hinges on Aoi’s ability to reconcile her human and Watcher identities, ultimately determining the fate of both realms.