Gema acts as guardian to Dejiko and Petit Charat (Puchiko), appearing as a floating yellow sphere with thin arms and circular hands. His facial features seem inverted to humans but remain natural for his species. Diligent and serious in caretaking duties, he frequently attempts to discipline Dejiko's behavior, only to face comedic retaliation from her. Despite this mistreatment, he persists with unwavering loyalty and concern for her well-being, often punctuating sentences with "gema" or "gema gema" in his speech.

He wields a blowgun with tranquilizer darts as his primary tool, though their effectiveness against targets proves consistently limited. During the *Omake Special* storyline, Gema plunges through a black hole into an alternate dimension, separating from the group. When Dejiko and others pursue him, he resists returning—displaying rare agency by defying his guardianship role until persuaded or coerced by the search party.

Originating from planet Di Gi Charat before relocating to Earth, Gema has unexplored familial ties including deceased parents and siblings. He consistently serves as a comic foil across series installments but remains absent from *Winter Garden*.