In a dystopian future, Japan is under the control of the GHQ, a multinational organization that took over after a catastrophic event known as the "Lost Christmas." The story centers on Shu Ouma, a high school student who lives a relatively ordinary life until he encounters Inori Yuzuriha, a member of the resistance group Funeral Parlor. Inori is on a mission to retrieve a powerful artifact called the Void Genome, which grants its user the ability to extract "Voids"—manifestations of a person's soul that take the form of unique weapons. During a confrontation with the GHQ, Shu accidentally activates the Void Genome, gaining the ability to extract and wield Voids.

Shu is drawn into the conflict between Funeral Parlor and the GHQ, led by the enigmatic Gai Tsutsugami, who seeks to liberate Japan from GHQ's oppressive rule. As Shu becomes more involved with Funeral Parlor, he discovers that his newfound power comes with significant consequences. The Voids he extracts are tied to the life force of their owners, and misuse can lead to severe repercussions, including death. Shu struggles with the moral implications of his abilities, especially as he is forced to make difficult decisions to protect those around him.

The narrative explores themes of power, responsibility, and the cost of rebellion. Shu's relationships with key characters, including Inori, Gai, and his classmates, evolve as the story progresses. Inori, who initially appears as a quiet and enigmatic figure, becomes central to Shu's journey, with her own mysterious connection to the Void Genome and the events of Lost Christmas. Gai, charismatic and driven, serves as both a mentor and a rival to Shu, pushing him to confront his fears and insecurities.

As the conflict escalates, deeper layers of the story are revealed, including the origins of the Void Genome, the true nature of the GHQ, and the events that led to Lost Christmas. The series blends action, drama, and science fiction, with a focus on the emotional and psychological struggles of its characters. The plot builds toward a climactic confrontation that forces Shu to confront the full extent of his powers and the sacrifices required to achieve his goals. The story concludes with a resolution that ties together the fates of its central characters, leaving a lasting impact on the world they inhabit.