Shioyama Koto

One day, Onitsuka Yamato, an office worker, kills another man who attacked him. When he took that man's life, a sound effect rang in his head informing him of his own strengthening and the acquisition of a spell. He had become a "murdelizer", a being whose level goes up when he kills someone. Yamato resolves to survive - even if it means killing people, kill someone within a week or else he will die.

Makoto Sakura, sixteen years old, finds himself without a place after dropping out of high school. Suddenly, an otherworldly relic appears before him. On that day, dungeons began to appear all over the world. Humans acquired a level system that completely overturned their previous values. Amidst this revolution, Makoto finds his place inside the dungeons. Acquiring cheat skills like "Experience Points x1000" and "Level Free," he becomes a level 10,000 powerhouse. As the strongest "Player," he embarks on dungeon exploration!