"Heavenly Delusion" is a science fiction manga set in a post-apocalyptic world where society has collapsed due to a catastrophic event. The narrative unfolds across two parallel timelines, intertwining the lives of its protagonists in a complex web of mystery and survival.

The first timeline centers on Maru and Kiruko, two teenagers traveling across a desolate Japan. Maru is a skilled fighter with a mysterious past, while Kiruko serves as his protector and guide. Their journey is driven by the search for a place called "Heaven," a sanctuary rumored to exist amidst the ruins of civilization. Along the way, they encounter dangerous creatures known as "Hiruko," monstrous beings that pose a constant threat. The duo also grapples with the remnants of human society, including bandits, cults, and enigmatic organizations with hidden agendas. As they progress, fragments of their pasts are revealed, hinting at deeper connections to the world's collapse and the nature of the Hiruko.

The second timeline takes place within a highly advanced, self-sustaining facility called the "Nursery." Here, a group of children live under the care of robotic guardians, completely isolated from the outside world. The children are unaware of the apocalypse and are raised with the belief that they are being prepared for a future mission. Among them, Tokio and Mimihime stand out as central figures. Tokio exhibits a strong sense of curiosity and defiance, while Mimihime possesses unique abilities that set her apart. As the children grow, they begin to question the purpose of their existence and the true nature of their confinement. Strange occurrences and cryptic messages from the facility's systems suggest a connection between the Nursery and the outside world's devastation.

The two timelines gradually converge, revealing a shared history and a profound link between the characters. Themes of identity, memory, and the consequences of scientific experimentation are explored as the story delves into the origins of the Hiruko and the facility's role in the world's downfall. The manga balances action, mystery, and emotional depth, creating a layered narrative that keeps readers engaged.

Maru and Kiruko's journey is marked by moments of camaraderie, tension, and moral ambiguity, while the children in the Nursery grapple with their growing awareness of the truth. The interplay between the two timelines builds suspense and gradually uncovers the larger picture, culminating in revelations that challenge the characters' understanding of their world and themselves. "Heavenly Delusion" is a thought-provoking exploration of survival, humanity, and the search for meaning in a fractured world.