"Eien no Hitomi" is a manga series that explores themes of immortality, loss, and the passage of time through a blend of historical and supernatural elements. The narrative centers on a young woman named Hitomi, who is cursed with eternal life after a tragic encounter with a mysterious entity. Her immortality comes at a cost: she remains perpetually youthful while everyone she loves ages and dies. This curse forces her to navigate centuries of human history, witnessing wars, societal changes, and personal tragedies, all while grappling with her own loneliness and the burden of her unending existence.

The story is structured across multiple timelines, beginning in feudal Japan, where Hitomi first gains her immortality. As the narrative progresses, it shifts to various historical periods, including the Meiji Restoration, World War II, and modern-day Japan. Each era introduces new characters who become significant to Hitomi, either as companions, adversaries, or fleeting connections. These relationships highlight the transient nature of human life in contrast to Hitomi's unchanging existence. Key figures include a samurai who becomes her first confidant, a scientist who seeks to uncover the secret of her immortality, and a young girl in the modern era who reminds Hitomi of her own lost humanity.

The plot intertwines Hitomi's personal journey with broader historical events, emphasizing how her immortality isolates her from the world she inhabits. Despite her efforts to find meaning or a way to end her curse, she is repeatedly confronted with the inevitability of loss and the cyclical nature of human suffering. The manga delves into philosophical questions about the value of life, the weight of memory, and the consequences of living beyond one's natural lifespan. Through its episodic structure, "Eien no Hitomi" paints a poignant portrait of a woman trapped in time, forever searching for connection and resolution in an ever-changing world.