The entity referred to as Ball Man is the being known as Gantz, who resides within the mysterious black sphere that gives the series its name. This individual is the unseen operator and master of the deadly game, controlling all functions of the sphere from the inside. While the sphere itself is a mass-produced object, with at least one factory in Germany confirmed to manufacture them, each contains a person with their own distinct personality and methods. The being inside the Tokyo room’s sphere is called Gantz, and other teams refer to their respective operators differently, suggesting each sphere’s inhabitant has a unique identity.

Very little is known about the background of this character. For most of the story, Gantz remains hidden within the black ball, never leaving its confines. It is not until later chapters that this being is seen fully for the first time outside of the sphere, revealing that the person inside can indeed come out. The personality of Gantz is inscrutable and detached, observing the resurrected humans it gathers with what seems to be a cold, clinical interest. It does not display明显的 emotions like empathy or malice, instead acting as an impartial, if cruel, game master who enforces its own set of bizarre and deadly rules. Its motivations are never fully explained, but its actions follow a consistent pattern: it summons recently deceased people, provides them with advanced weaponry and protective suits, assigns them missions to hunt down and kill alien targets, and scores their performance.

The role of Gantz in the story is that of the primary antagonist and facilitator. It is the source of all the supernatural technology within the game, including the ability to teleport people, provide advanced weaponry, and even resurrect the dead. Gantz sets the mission parameters, reads the scores, and offers a menu of one hundred point rewards to the highest performers. These rewards can include erasing memories and allowing a player to leave the game permanently, or reviving a deceased player or another person who has died. Gantz also serves as an enigmatic force that drives the plot forward, as the characters are forced to participate in its deadly hunts with no choice but to follow its directives or face elimination.

Key relationships for Gantz are primarily functional rather than personal. It interacts with all players, but certain individuals have more significant connections to it. The player Nishi is shown to be quite familiar with Gantz, suggesting a longer history or deeper understanding of the sphere’s nature. In a significant turn of events, the player Reika uses her earned one hundred points to make a selfish request of Gantz: to create a second, copy of her teammate Kei Kurono. Gantz agrees to this request and performs the duplication, demonstrating its power to grant almost any wish, even one that creates a copy of a living person. This act shows that while Gantz typically enforces its violent game, it is also a tool that can be used by the players who have earned enough points.

The development of this character is minimal but significant. For the vast majority of the narrative, Gantz is a disembodied voice and the mysterious black ball itself. Its development comes when it finally emerges from the sphere. During the catastrophic final arc known as the Katastrophe, Gantz takes a more active role in assisting the Tokyo Team. It helps them by removing the explosive bomb chips from their heads, freeing them from a method of control and punishment it had previously used. Furthermore, when the team needs to rally other hunters for a major mission, Gantz broadcasts Kurono’s recruitment message to all the other black spheres around the world, acting as a communication hub and coordinator in the fight against a greater alien threat. Finally, Gantz is last seen being hacked and attacked by a mob of unknown insectoid assailants, meeting an ambiguous and violent end in its own room.

The notable abilities of Gantz are vast and seemingly impossible. It can teleport people across the globe and retrieve them. It possesses the power to perfectly scan, copy, and resurrect a deceased person, removing every trace of their old body down to the last drop of blood and generating a completely healthy new version. Gantz can also restore any player who has died during a mission, bringing them back to the state they were in before being sent out. It has the ability to manipulate memories, often erasing them when a player chooses to leave the game, though some fragments may linger. The sphere and the individual inside it are invulnerable to the weapons given to the players; attempts to shoot the sphere with the X-Gun or stab it with a blade have no effect. Finally, Gantz can grant wishes to players who accumulate one hundred points, with options including the revival of a dead person, the erasure of memories to leave the game, or even the creation of a copy of a living individual.