Masato Akitsu, alias Masaki Kihara, is a genetically engineered creation designed exclusively to command the formidable mecha Zeorymer. Crafted by a clandestine organization, he was raised by adoptive parents compensated to groom him for his predestined role. His illusion of normalcy shatters upon his adoptive father’s dying revelation and interactions with Miku Himuro, a girl intrinsically tied to Zeorymer’s core systems.

Piloting Zeorymer activates implanted memories of Masaki Kihara—the mecha’s brilliant, ruthless creator—triggering a fractured psyche torn between Masato’s innate humanity and Masaki’s calculating cruelty. This duality intensifies as Zeorymer’s protocols initially favor Masaki’s consciousness, yet gradual integration forges a coalesced identity blending Masato’s empathy with Masaki’s tactical genius.

Pivotal moments include a morally fraught incident involving Miku, spurred by Masaki’s manipulative impulses, underscoring the ethical turbulence of his fractured self. Masato’s path escalates into defiance against Nematoda, the shadow entity coveting Zeorymer’s power. In the climax, he confronts Masaki’s clone piloting a duplicate Zeorymer, their clash triggering a fusion of mechas and exposing an extradimensional energy source. The saga culminates in Masato and Miku intercepting a deuterium bomb’s cataclysmic blast to shield Earth, their survival left hauntingly unresolved.

The manga delves into visceral themes of genetic experimentation and psychological fracture, whereas the OVA distills the narrative to his internal metamorphosis from pawn to self-determined entity. Both iterations chart his evolution, balancing engineered obligation with hard-won autonomy.