Rucchi appears as a minor antagonist, one half of a hunter duo alongside Gocchi, operating under primary antagonist Gorgo's command. Their core task is pursuing the young Pteranodon protagonist, Punon, throughout her journey.

Functioning as comedic foils, Rucchi and Gocchi repeatedly fail to capture Punon. They first corner her in a valley, but the unexpected arrival of Tyrano frightens them away before they succeed. Their pursuit leads to another ambush near Tyrano's cavern home, thwarted by Tyrano's intervention; Punon mocks their retreat with a gesture, shaking her posterior at them.

Later, Rucchi and Gocchi are seen stealing fruit from herbivorous dinosaurs. They encounter Punon again during her travels with Tyrano and Tops; Punon taunts them further with an eyelid pull before escaping.

Rucchi's final involvement occurs during the climax within the Herbivore Paradise. Alongside Gocchi, this character participates in Gorgo's coordinated attack on the valley inhabitants, maintaining their role as minor enforcers executing Gorgo's destructive objectives.

The narrative provides no details regarding Rucchi's background, origins, motivations beyond following orders, or personal development. Their presence primarily creates obstacles for the protagonists and contributes comedic elements through repeated failures and reactions to Punon's defiance.