The Neo Zeed are a group of assassins stationed in Tokyo, Japan, although they have a stronghold in the Ibakari Province. For reasons unknown, the organisation, one with an outside appearance as a respectable corporation, kidnapped a girl called Naoko and poisoned the sensei of Joe Musashi, a ninja trained in the ways of bushido.
Neo Zeed was once led by The Void, often known as "The Fifth Element", who wielded great martial arts skill and supernatural magic powers. Beneath him were The Four Elements (Fire, Water, Air and Earth), highly-skilled ninja who did their master's bidding. Every other assassin in the company was a lowly henchman, yet even they were trained thoroughly in ninjitsu, being able to halfway keep up with Musashi, wielding swords and shurikens. However, when Musashi defeated The Void and sent a warning to them to leave him alone, The Four Elements deserted the company and worked for the Yakuza. Other employees of the Neo Zeed are licensed guards who patrol the main building and keep out intruders using automatic machine-guns.
At the end of The Art of War, The Void alluded to something that required more attention than Musashi. This was never touched upon again despite two more stories and that The Void met Musashi again very shortly after this adventure.
During the events of the Shinobi series, no members of the Neo Zeed were killed by Musashi, although many were knocked unconscious or were severely injured. It remains unknown whether the assailant in the elevator who's rope was cut survived the fall.