Yugo Kasumi is a high school student living in a small, quiet village in Ibaraki Prefecture. After the death of his parents, he is forced to live with his uncle and aunt, who openly despise him and view him and his loyal dog, Iggy, as useless burdens. His situation at school is equally grim; three former childhood friends, led by the sociopathic Nemoto, now bully Yugo relentlessly. His only genuine companion and comfort is Iggy, his faithful dog.

This oppressive daily life is shattered when the ZQN infection, a disease that transforms humans into homicidal zombie-like creatures, reaches his rural town. As society collapses overnight and the undead begin to roam the streets, Yugo initially finds that the apocalypse has ironically given him a chance to escape his abusers. However, his freedom is short-lived. Nemoto and his gang see the chaos not as a threat, but as an opportunity. In a world where the weak are devoured, the bullies decide that the law of the strongest will now prevail, and they force Yugo and Iggy to become their tools for survival.

The narrative follows Yugo and his dog as they navigate the terrifying early days of the outbreak in Ibaraki. Unlike the main series protagonist who struggles with hallucinations, Yugo's fight is largely an external one against a double threat: the ever-present ZQN and the unchecked cruelty of his fellow humans who have embraced the anarchy. The story explores themes of cyclical abuse, as flashbacks reveal that Yugo's tormentors were once victims themselves, creating a vicious cycle that not even a zombie apocalypse can break.

A notable early arc focuses on Yugo and Iggys struggle to escape their hometown while being coerced by Nemotos group to scavenge and fight for them. The story, drawn by Kazuya Fujisawa in a style that mimics the gritty, bizarre tone of the original series, ultimately chronicles whether a boy and his dog can survive not just the end of the world, but the monsters created by the collapse of human decency.