Zaza is the leader of the tribe of the lost children in Boutoume.
Zaza and his adoptive sister, Sachya, were among the children aboard the bus that fell off the cliff of Hekseville and ended up in an abandoned village far below Hekseville. He took on a role of responsibility and became the children's leader. Not wanting to break their hearts, Zaza lied to them, leading the children to believe that help was coming and their parents were still waiting for their return.
At one point, he "let" Sachya go, and the latter was able to get back to Hekseville. Because time is off in the land below, years had already passed on land while less time passed for the children. Zaza and the others remained young while his sister aged. Sachya became a Shifter and became known as Raven. Zaza no longer recognized her, and she never reintroduced herself.
When the Shifter known as Kat or the Gravity Queen came down, the children caught her and took them to their village in a cage. Zaza was initially hostile with the uncooperative stranger, until the girl saved them from Nushi. Later, Raven returned and helped fend off Nushi once more. Kat managed to open and make the Ark function, and they escaped Boutoume with Raven while Kat was left behind.
In the ending, he and the rest of the lost tribe made it back to Hekseville. But currently resides in the Ark due being in a coma caused by unknown reasons.