The protagonist, Kaneko Yuu, is a young man living on a small, isolated island whose closed-off environment he finds suffocating. His dream is to escape this life and find a job in Tokyo. His plans are violently derailed when the island becomes the epicenter of a mysterious infection. Soon after the outbreak begins, the residents around him start showing symptoms, transforming into beings that relentlessly attack the uninfected. The infected possess a terrifying regenerative ability; even if their limbs are cut off, they simply grow back. More horrifyingly, each severed piece does not die but instead grows into a fully new, separate infected body. Faced with an enemy that can multiply exponentially with every attempted defense, the remaining ordinary humans must fight for survival against these former friends and neighbors in a panic horror scenario. The key narrative arc is the desperate struggle of the non-infected to survive on the island, trapped with creatures that turn violence into a means of replication. The core conflict is a primal war of attrition between original humans and the regenerative "former humans."