An unexpected accident put him into an eternal sleep, but when he wakes up, he finds himself transported to the world of the game he was playing! Reincarnated as the game's main character, a beautiful vampire princess, "he" is the ruler of a huge demon empire, surrounded by the followers he had raised in the game...! (Source: Garden Comics, translated))

One day, Yamato Onitsuka, 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 Onitsuka resolves to survive even if it means killing people as and to keep on living he needs to kill someone within a week or he will die.