Plot
Killy, a silent loner possessing an incredibly powerful weapon known as a Gravitational Beam Emitter, wanders a vast technological world known as "The City". He is searching for Net Terminal Genes, a (possibly) extinct genetic marker that allows humans to access the "Netsphere", a sort of computerized control network for The City. The City is an artificial structure of immense volume, separated into massive "floors" by nearly-impenetrable barriers known as "Megastructure". The City is inhabited by scattered human and transhuman tribes as well as hostile cyborgs known as Silicon Life. The Net Terminal Genes appear to be the key to halting the unhindered, chaotic expansion of the Megastructure, as well as a way of stopping the murderous robot horde known as the Safeguard from destroying all of humanity.
Along the way, Killy meets and joins forces with a resourceful engineer named Cibo. Their quest is indirectly supported by the City's Authority, which is unable to stop the Safeguard from opposing them. Together, Killy and Cibo meet a young girl named Sanakan and a tribe of human warriors called the Electro-Fishers. Killy's cybernetic abilities are restored after he is attacked by a high-level Safeguard, which turns out to have been Sanakan in disguise. She transforms into her Safeguard form and attacks the Electro-Fishers' village when discovered. Killy and Cibo defend the Electro-Fishers by bringing them to the cylindrical megastructure of Toha Heavy Industries. Here they meet Mensab, an AI independent from the Administration, and her guardian Seu, a human. The megastructure is ultimately destroyed due to attacks by Silicon Life and Sanakan, but Mensab is able to give Cibo a sample of Seu's DNA.
Killy and Cibo next come to a region of the City ruled by a group of Silicon Life, where they ally with a pair of "provisional Safeguards" named Dhomochevsky and Iko. Seu's DNA is stolen by the Silicon leader, Davine, who uses it to access the Netsphere. Dhomochevsky sacrifices his life to kill Davine, but not before she downloads an extremely powerful Level 9 Safeguard from the Netsphere which manifests in Cibo's body. The Cibo Safeguard destroys the entire region.
14 years later, Killy's body repairs itself from the attack and he continues his journey. He meets a human whose physical body is dead and whose consciousness is preserved in a device resembling a USB stick, and takes her with him. Upon eventually finding Cibo again he discovers that she, having lost her memory, was eventually rescued by Sanakan, who is now allied with the Authority against the rest of the Safeguard. Cibo's body is incubating a "sphere" which contains both her and Sanakan’s genetic information. Ultimately, Cibo and Sanakan both die in a final confrontation with the Safeguard, but Killy survives and preserves the sphere. The digital consciousness Killy picked up earlier is seen in human form in the Netsphere, recounting Killy’s quest to other entities an unknown amount of time in the future. She is told that Killy’s journey to the outside of the City will be longer and harder than anything that came before. Killy finally reaches the edge of the City, where he is shot in the head and incapacitated, but a flood of water carries him to the surface of the City where stars are visible and the sphere begins to glow. In the final page, Killy is seen fighting in the corridors of the City again, alongside a small child wearing a hazmat suit.
