Poco, whose name is rendered in Japanese as Poko, is a young boy who appears in the first part of JoJo's Bizarre Adventure, Phantom Blood. He is introduced as a small, scruffy street child living in an English village during the late nineteenth century. He has no supernatural abilities and is an ordinary boy, though his circumstances place him at the center of dangerous events.

Early in the story, Poco falls under the mental control of Dio Brando, who uses him as bait to lure Jonathan Joestar and his companions into a trap. While under this influence, he steals from the group's supplies, appearing as a mischievous and cowardly child. After breaking free of Dio's control, he becomes an ally of the Joestar group.

Poco's primary motivation is to save his sister, who has been taken captive by Dio. This personal stake drives him to accompany Jonathan and the others on their quest despite his fear and lack of combat training. His relationship with Jonathan develops as he observes Jonathan's courage and resolve, and Jonathan's example inspires him to find his own bravery. During the fight against Tarkus, when Jonathan is in danger of losing, Poco shows genuine courage and is willing to risk his life to help the group, proving himself useful in a moment of crisis.

His development is marked by a shift from timidity and self-preservation to selfless acts of loyalty. In the original story, after separating from the group, he is captured by local bullies and nearly beaten, which further highlights the danger surrounding him. His bravery also helps rally the townsfolk against the undead threats that appear in his village.

Poco remains a supporting figure rather than a fighter, and his significance lies in his humanity and growth. He represents an ordinary person drawn into an extraordinary conflict, and his loyalty to Jonathan and his sister defines his role in the story.