A strange and cruel world that takes away your memory, but gives you strength in return... the opportunity to receive it. A man who woke up in an unfamiliar city, who received the System as a gift, but wants to return what was taken from him. Aspiring, but very soon realizing that it is extremely difficult to do this in a changed world full of monsters. Monsters, recently or long ago, but previously formerly people exposed to a powerful virus. He deprives some of their minds and transforms them into monsters. Others, who turned out to be resistant to the infection, are endowed with new, unique opportunities. So it remains for a person deprived of a significant part of his own “I”, who received the nickname Demon from the world itself, to move forward, leaving behind corpses and death, pain and regrets about what did not happen.