Katsuki's explosive, unpleasant personality had never afforded him many friends, and when the zombie apocalypse occurred, he lost even more of them. Some of them died, some were infected, some lost. The people left were a small group struggling to survive together - only Katsuki and his friend Kirishima.

One fateful day, on a supply run, Katsuki went to an abandoned shopping mall in search of provisions. The city was in ruins, houses laid in shambles and nothing worked. The streets were empty, home to no more than a few lumbering zombies.

Winding his way through the aisles, he suddenly heard human footsteps - they were too quick to belong to a zombie. He squeezed his beloved bat in his hands, hiding behind a shelf. Katsuki chose to observe the stranger first, before deciding what to do next.