Rat is a young orphan surviving on Hong Kong's streets, an unwilling member of a criminal gang where he endures harsh treatment from older members. His life transforms upon encountering Elaine, a teenage girl possessing animal-like instincts and potent psychic abilities. They forge a bond, finding moments of happiness together despite their hardships.

When a gang member attempts to assault Elaine, Rat is present. Diana, Elaine's sister, intervenes in a cybernetic combat suit, killing the assailant. Pursued by agents of the Kuryu Institute seeking to capture Elaine for military experiments, Rat and Elaine flee onto a subway train. Cyborg agents Wakayama, Amachi, and Katsu forcibly stop the train, causing Rat to sustain a head injury and lose consciousness.

The precise circumstances of Rat's death remain unclear. He is next seen bleeding from his head while held by Wakayama, the fatal injury's origin ambiguous—potentially from the subway stop or Wakayama's direct action. Rat loses consciousness again after Elaine witnesses Diana's apparent death. Wakayama abandons him, and Rat's body is later discovered on a steel beam at a construction site.

Following his death, Rat's ghost appears to Elaine during her first rampage as Genocyber. His spirit bids her a final farewell before passing on. Elaine's discovery of Rat's body and her ensuing despair trigger a catastrophic explosion that annihilates Hong Kong.