The narrative picks up with the protagonist, a young man, scavenging for supplies in a deserted town. He demonstrates a hardened pragmatism, using a stone to break into a house and a crowbar to gain entry, prioritizing survival over noise. Inside, he finds signs of a recent occupant, including an opened can of food, but no immediate threat. His search for sustenance is interrupted by the discovery of a man who has hanged himself on the stairs, a grim testament to the despair of their new reality. The protagonist shows no emotional reaction, having become desensitized to death. He continues his search, finding little of value on the first floor, and proceeds upstairs.
The protagonist finds temporary refuge in a high-rise apartment, noting the silence and the absence of any functioning utilities. He establishes this as a safe haven, securing the entrance. His meager meal of canned food highlights the scarcity of resources. He then begins to explore the apartment, finding more canned goods, rice, and essential supplies like medicine. He also discovers a child's room, which triggers a brief, melancholic reflection on his past life as a normal high school student. He finds an old cassette player and listens to a protest song, contemplating his own survival and the widespread despair that has led many to suicide.
The story then shifts to the protagonist's perspective two weeks later, as he ventures out from his apartment. He observes the devastated cityscape, a stark contrast to the normalcy of his past. His encounter with a group of infected individuals, who are cannibalizing a corpse, further emphasizes the brutal reality of their world. The infected are described as humans transformed by a virus, driven by insatiable hunger and aggression, possessing superhuman strength and resilience. The protagonist reflects on the rapid collapse of civilization and the dwindling hope for a return to normalcy.
He recounts his past as a high school student and the gradual descent into chaos, from distant news reports of riots to the realization of a global pandemic. He describes the initial disbelief and the attempts to maintain a semblance of normal life, which ultimately proved futile. His current situation is one of constant vigilance and survival, relying on his speed and agility to evade the infected.
The narrative then introduces Tachibana Yui, a middle school student, whom the protagonist encounters in a looted supermarket. Yui has fled her former shelter after it was overrun by the infected. Despite his initial hesitation to take on the responsibility of another survivor, the protagonist, moved by her plight and the need for companionship, decides to let her join him. Their journey is fraught with danger, and they narrowly escape a horde of infected individuals by hiding in a locker at a gas station.
Their next destination is a former middle school, now a makeshift shelter, which they discover has been overrun and destroyed. The scene is one of carnage, with numerous corpses and signs of a desperate struggle. The protagonist, hardened by his experiences, is unfazed, while Yui is deeply disturbed. They decide to search the school for supplies, driven by their dwindling resources.
Inside the school, they find evidence of a desperate fight against the infected, including spent shell casings. The protagonist deduces that the infected likely originated from within the shelter itself. They discover a young girl, Aina, who has been trapped in a gymnasium storage room for two days. Aina's story reveals the tragic fate of her family and the other inhabitants of the shelter.
The protagonist, despite his growing weariness and the emotional burden of his past actions, agrees to help Aina search for her family, a decision that weighs heavily on him. He discovers the bodies of Aina's mother and brother, and later, her father, who had become infected and was killed by the protagonist himself. He lies to Aina, telling her that her family likely escaped, unable to bear the thought of crushing her hope.
The group continues their journey, now three strong, heading towards another rumored shelter. They face challenges such as a destroyed bridge and the constant threat of the infected. The protagonist grapples with the responsibility of protecting Yui and Aina, feeling the immense pressure of their lives resting on his shoulders. He reflects on his own limitations as a survivor, a former high school student whose only real asset is his speed.
Their journey leads them to a city with a high population density, implying a large number of infected. They find a functioning convenience store, but the lingering smell of decay serves as a constant reminder of the world's grim state. The protagonist's leadership role becomes more pronounced as he makes decisions about their route and safety. He struggles with the emotional toll of his responsibilities, particularly the lie he told Aina about her family.
The narrative concludes with the group facing a new obstacle: a destroyed bridge over a river. The protagonist's attention is diverted by the sight of a large number of infected individuals gathered on the road ahead, forcing them to reconsider their path.
