Gema is a floating yellow spherical creature with small thin arms and circular hands. His facial features appear inverted, though this orientation is standard for his species. Originating from planet Di Gi Charat, Gema serves as guardian and chaperone to Princess Dejiko, accompanying her to Earth. He oversees her daily activities and attempts to curb her impulsive behavior, but is frequently overruled or bullied by her, consistently appending "gema" to his sentences.

Gema exhibits a serious and diligent personality, acting as the voice of reason. Despite efforts to maintain order, he is easily swayed by Dejiko’s whims and endures her retaliatory actions without lasting resentment. His primary ability involves using a blowgun equipped with tranquilizer darts to subdue targets, though its effectiveness varies. In "Reiwa no Di Gi Charat," he employs an attack called "Yellow World," incorporating a stylized yellow submarine as a visual allusion.

Across the franchise, Gema’s role remains consistent. "Panyo Panyo Di Gi Charat" depicts him as Dejiko’s sole companion during her childhood on their home planet, reinforcing their long-standing relationship. "Di Gi Charat Nyo!" positions him as a steadfast overseer of Dejiko’s princess training on Earth, maintaining characteristic patience amid chaos. The "Winter Garden" specials, set in an alternate future where Dejiko and Puchiko live as humans, omit his presence, indicating a divergence. "Reiwa no Di Gi Charat" reaffirms his core traits as Dejiko’s long-suffering guardian, navigating new dynamics with corporate deities like Broccodess while continuing duties at the Akihabara Gamers store.