When the mysterious asteroid “Hakon” collides with Earth, the world devolves into an apocalyptic wasteland overrun by zombies and mutated beasts. Betrayed and left to die by a trusted comrade, Hirai Shu swears a vengeance so fierce that it pulls him back in time to the moments right before the pandemic strikes, granting him a powerful Skill System in the process. Once a helpless target of severe bullying, Shu returns not as a victim, but as a cold-blooded avenger shrouded in murderous intent. Utilizing his future survival experience and his newly acquired system abilities, he deals ruthless retribution to his former bullies and backstabbers while rising to become the ultimate survivor—determined to protect the true comrades who sacrificed everything for him in his past life.