HGZKILLER is an international secret agency that specializes in cultivating and gathering killers. There are countless underground secret organizations. "" Is located at the highest level of the HGZ organization. Its popularity has persisted for a long time, and it is an ideal choice for HGZ lone wolf killers. (Note: Members of the highest-level organization enjoy unique powers.) "" Is the number one top killer codenamed "Zero." ""'S ten thousand year old second son is codenamed "Zero" (Note: The codenames of the members of the "" organization all start with the word "zero"!!!)
Concept: Forbidden love