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.
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He had become a "murdelizer", a being whose level goes up when he kills someone.
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Yamato resolves to survive - even if it means killing people, kill someone within a week or else he will die.
