Darth Bero commands the Robot Tribe on the planet Kirakira, outwardly pledging full allegiance to the Kariage family—worshipped as deities by his tribe—and actively advancing their schemes. Beneath this facade of loyalty, he privately questions the Kariage family's motives and actions. His leadership drives the Robot Tribe's aggressive expansion from their desert domain into the forested territories of the peaceful Senobi tribe, intensifying the conflict between them.

Visually, Darth Bero presents a distinctively goofy facial expression, complete with a perpetually protruding tongue. Yet, in critical or intense moments, he replaces this with a mask bearing an angry countenance. This shifting appearance mirrors his dual role, oscillating between comedic relief and antagonistic leadership.

His arc culminates in the series' conclusion with a pivotal revelation: unmasked, he is exposed as Zenjirou Kariage, the long-vanished husband of Maneko Kariage. This disclosure solves the central mystery of the Kariage patriarch's disappearance and recontextualizes his earlier actions and concealed skepticism toward his own family.