Originating from "Let's Go! Anpanman," Melonpanna debuted in episode 200, "Melonpanna is born." Her head is melon bread, featuring a criss-cross pattern and a cursive "m" insignia on her chest. She wears a dark green uniform with a light green belt, gloves, boots, and a cape green on top and orange underneath, complemented by large green eyes, a small green nose, and orange cheeks.

Uncle Jam created her using the nectar of a flower of love, establishing her as a younger sister to Anpanman. This origin contributes to her gentle, caring, honest, and sensitive nature, often nurturing Creampanda like a younger brother. Despite her kindness, she possesses super strength and will fight when necessary, though she avoids conflict.

Her primary ability is the "Melo-Melo Punch," which induces euphoria or incapacitation, sapping opponents' will to fight. She generates melon juice as her energy source. Depleting this juice or separation from Rollpanna during Rollpanna's evil phases can cause Melonpanna to faint. Her deep emotional bond with Rollpanna borders on obsession, driving her to seek constant closeness and causing distress during separation. Melonpanna's presence is often pivotal in restoring Rollpanna's good heart when overtaken by evil.

She assists Anpanman with patrols and deliveries. Her story extends to the film "Soreike! Anpanman: Yūreisen o Yattsukero!!," where she and Rollpanna befriend the horse Marin, though Baikinman exploits Rollpanna's instability. Across the franchise, Melonpanna consistently emphasizes compassion and the importance of familial bonds, serving as an emotional anchor for Rollpanna and a supportive figure within the hero group.