Dungeons begin to appear in the world, and people are called "Hunters" because they gain special powers. 100 years after these dungeons appeared, another FAQ-level dungeon appears.
The boss of this dungeon is the Lord of the Dead and everyone who enters that dungeon dies. Due to the power of the Lord of the Dead, they cannot clear the dungeon. The immortals break the dungeon and come out, and the immortals spread throughout the world. As a result of these events, a literal apocalypse begins.
While these events are happening, Kage is trying to clear an SS-level dungeon alone. Kage creates an army of Death Knights and kills all the monsters in the dungeon. After clearing the dungeon, when he comes out, he sees how terrible the end of the world is and cannot believe it.
He spreads around the world with his army of Death Knights, killing immortals one by one and gaining knowledge about the world. All people in the world are dead and the world is under the control of the Lord of the Dead.
Kage finds the Lord of the Dead's Castle thanks to his army and kills all the undead in the world before entering. When he enters, the Lord of the Dead rises from his throne and calls out, "I have been waiting for you for a long time, the most powerful Necromancer in the world."
Kage cannot hold his anger at the deaths of everyone he knows, and draws his sword and begins to fight the Lord of the Dead. When the swords clash, the castle collapses and the fight continues outside.
After a long time, the Lord of the Dead reveals a secret trump card and sends a weapon on them from space. However, Kage is gravely injured and with one last idea, he burns half of his soul and summons the "Lord of Death", the most powerful person in the universe. When the Lord of the Dead sees the Lord of Death, he kneels down and asks, "Why are you here, sir?" he asks.
Just before answering the question, the Lord of Death pulls out the Kage's sword and cuts the Lord of the Dead into pieces. When the Lord of the Dead dies, Kage finds a mysterious item and pockets it. Then, the Kage turns to the Lord of Death and says, "For summoning me to this disgraceful world, I will kill you in the same way and take your soul."
The Lord of Death rushes forward and attacks with his sword. Kage dies and the item in his pocket glows. He opens his eyes in the middle of the city in another world and looks around. The buildings became old and collapsed, and the city began to progress. He sees someone at the beginning of the street and greets him, "Where is this place?" he asks but doesn't hear.
He goes to him and repeats the same things and turns the person towards him. He looked like a zombie and made weird growling noises. Kage wonders why the zombie isn't attacking him and looks through the building's window to see his own reflection. He realizes that he is a zombie and that he is reborn as a zombie in the zombie world.