Genzou Kuruma is a scientist leading the sect known as the 13 Doctors or Apostles, dedicated to awakening their god. He is the father of Shinichi Kuruma and husband of an unnamed woman whom he subjected to fatal experiments. These experiments, along with attempts to transform his son into a non-human entity, stem from his desire to transcend humanity. His actions directly caused his wife's death and motivated Shinichi's quest for vengeance against him.

Genzou orchestrates the creation of genetically altered beings called "New Humans" or "Newmen," capable of shapeshifting into monsters. He seeks a specific blood type necessary for the god's revival, found in both Shinichi and a young girl named Ayaka Sanders. To obtain this blood, he orders relentless attacks on both targets, showing no regard for collateral damage or civilian casualties. His faction caused the "Great Destruction," a catastrophic event involving earthquakes that devastated Shinjuku.

As part of his plan, Genzou creates clones of god-like entities using isolated blood from Maria Tengai and his own research. Among these clones is Noah, a being with a third eye designed to enact divine punishment. He produces multiple versions of these clones, ranging from benevolent to wrathful manifestations. His methods include manipulating biological elements, such as injecting Ayaka with pluripotent cells derived from Shinichi to establish a psychic link between them, intending to use this connection to further the god's awakening.

Throughout the conflict, Genzou remains committed to his goal, viewing the sacrifices and destruction as necessary. His background as a father and scientist is overshadowed by his abandonment of ethical and familial bonds, positioning him as a figure of absolute antagonism driven by apocalyptic ambitions. There is no depicted redemption or change in his motives.