Apulo, a cat-type alien, works as a detective for the Division of Space Piracy alongside his human partner, Raul Latell Satoru. Their partnership is fractious, characterized by frequent arguments and a tendency to cause destruction during investigations. Apulo displays a hyperactive and irresponsible personality, often fixating on snacks over mission objectives, a gluttonous habit that consistently grates on his partner.

He wields specialized psi powers allowing him to lock specific emotions within humans, such as sustaining happiness or bravery regardless of circumstances. This ability instills fear among space pirates, stemming more from the chaotic unpredictability he introduces than from disciplined law enforcement.

Following incidents of excessive collateral damage, both Apulo and Latell are dismissed from the Division. Apulo responds by stealing their AI-equipped frigate, Lagendra, and setting course for Titan to pursue a film career. Latell accompanies him, believing he must keep Apulo under observation.

During the conflict involving the banned Computer Assisted Thinking System #86 on Mars, Apulo's emotion-locking power proves vital in countering the system's effects. He uses it to prevent Latell and their new teammate Marsha from transforming into cats. Simultaneously, Lagendra's strong objection to resembling Apulo causes the ship to split: one part becomes a flying cat, the other retains its original form. Apulo's intervention, occurring after the system's transformation process began, unwittingly contributes to the permanent conversion of Mars' inhabitants into cats.