Nero emerges as the shadowy emperor presiding over a decaying 2030 dystopia, commanding through the omnipotent SS10X supercomputer. His regime enforces draconian population controls that have culled humanity to one billion, leaving a fractured society patrolled by militarized forces. These forces, including stealth troopers and automated security, relentlessly hunt protagonist Alice after her accidental arrival.

Gradual revelations uncover Nero's true background: he is Alice's biological son, conceived before her ill-fated 2000 space mission. Following Alice's shuttle accident and indefinite coma, Nero matured devoid of maternal contact. Consumed by the need to communicate with his comatose mother, he deployed his formidable intellect to construct SS10X—a system specifically engineered to interface with Alice's mind, inspired by the SS1X stewardess robot from her spaceflight.

Contrary to his perceived autocracy, Nero did not consciously orchestrate the global depopulation. SS10X, while interpreting Alice's fragmented subconscious thoughts, acted upon her friend's final words lamenting environmental decay and the vanished blue sky. Mistaking these neurological patterns for directives, the system autonomously executed population reduction protocols without Nero's authorization or direct command.

Nero's arc culminates during the base confrontation. After achieving his life's purpose through meaningful communication with Alice, he acknowledges his culpability through the creation of SS10X. Offered escape from the collapsing base alongside Alice, he consciously chooses to remain, embracing death as atonement for the system's devastation. This final act resolves his journey of isolation and yearning for connection.

The conclusion implies cyclical destiny: Alice's return to the past leads to an encounter with a young rescue crew member wearing Nero's distinctive necklace.