Cocopo is a creature known as a Hororon bird and serves as the loyal mount and companion to the noblewoman Rulutieh in Utawarerumono: The False Faces. Her appearance is distinctive, with a head covered in white feathers, a dark gray body, and a red tail marked with a black arrow pattern. A tuft of black, red, and white plumage extends from her head, and she is typically fitted with a red saddle secured by brown straps. Despite being a bird, Cocopo is unable to fly.

In terms of personality, Cocopo behaves like a dedicated pack animal, but her relationship with Rulutieh transcends that of a simple master and steed. She considers Rulutieh a friend and family member rather than an owner. Cocopo possesses the ability to read her master's emotions, to which she is highly attuned. She is naturally distrustful of strangers and keeps her guard up around unfamiliar humans. However, she is fiercely protective of those she cares about, especially Rulutieh. When she perceives a threat or an insult directed at her master, she becomes relentless in her attacks, sometimes going into a berserker state that even Rulutieh cannot control.

Cocopo plays a significant role as a battle companion and a mode of transport for Rulutieh throughout the story. Her motivations are simple and driven by loyalty: to protect Rulutieh and to assist her in traveling to the capital of Yamato as a messenger carrying tribute. One of the most notable aspects of her role involves her unique relationship with the protagonist, Haku. When Haku accidentally bumps into Cocopo, she reacts with unexpected affection, rubbing her head against him and following him persistently. This behavior shocks Rulutieh, who states that she has never seen Cocopo act so affectionately toward anyone else. Haku seems to be the only other person besides Rulutieh to receive such warm treatment from her. In contrast, she shows natural hostility toward other creatures like the giant tiger Mukkuru, though this animosity eventually fades into a friendship where the two are seen eating and sleeping together.

Cocopo displays several notable abilities. Beyond her talent for reading emotions, her primary capability is combat-oriented. When enraged or protective, she is a formidable fighter who can chase off bandits and enemies, leading some to call her a demon or a god of misfortune due to her size and ferocity. Her protective nature is so strong that she will kick away anyone she perceives as a threat to her bond with Haku and Rulutieh, such as when she prevented another character from sitting between them. Throughout the narrative, Cocopo shows development in her capacity for forming bonds, initially being aloof with strangers and other animals but eventually forming a close friendship with Mukkuru, and even waving goodbye when he departs.