A mysterious entity known as the Goddess infects people at the moment of their death, transforming them into unthinking, destructive creatures called heroes. These beings believe they are fighting monsters in a dream world, following the beautiful Goddess’s orders, but the monsters they slaughter are actually fellow humans. The transformation preys on dying children, showing them a vision of a perfect world to secure their agreement. Only people under the age of twenty can even see these heroes, leaving the burden of fighting them to children and teenagers.

In modern Japan, where hero attacks have leveled entire sections of Tokyo, an elite unit named Charon stands as the primary defense. Charon is composed of survivors of a devastating hero attack and is led by a young man named Azuma, who has lost everything to the heroes and seeks only their destruction. The unit uses powerful organic weapons to combat the heroes effectively. Azuma firmly believes saving the heroes is impossible and that extermination is the only path forward.

A headstrong young scientist named Kaguya Shinohara joins Charon with a radically different goal. Rather than destroy the heroes, she researches methods to reverse the transformation and return them to human form. Kaguya possesses a unique ability that sets her apart from everyone else: she can actually speak with the heroes, something previously thought impossible. This ability forces Azuma to confront the possibility that his total war approach might not be the only option. Kaguya is reassigned from her laboratory to the frontlines against her initial wishes, placing her directly into conflict with Azuma and his unit, who struggle to accept her existence after what they have lost.

The first major narrative arc introduces the core philosophical conflict between Azuma and Kaguya as they clash while being forced to work together on the battlefield. Kaguya becomes directly involved in an assault, and the Charon team begins to see promise in her research approach. She also starts discovering something fantastic and terrifying about herself. The first volume concludes with a major climax that feels like a natural endpoint but leaves room for continuation.

A second volume takes place two months after the battle with the Goddess in Akihabara. A new female member named Haru Takanashi is assigned to Charon for rehabilitation and training, though it becomes clear her career is being monitored by higher authorities. Haru proves to be an even more formidable presence than Azuma, believing obsessively in saving others with a self-righteous conviction that Azuma finds laughable. This volume explores themes of encouragement, envy, sarcasm, and betrayal.

In the third volume, Kaguya has her spirit absorbed into the spiritual world of a hero. Azuma and his companions must protect the girl who has lost her heart while confronting the truth behind the heroes and the Goddess herself. This arc brings the team face to face with the fundamental mysteries of the transformation, forcing them to question everything they thought they knew about the enemy they have been fighting.