Originating from melon bread crafted in Uncle Jam's bakery, Melonpanna possesses a kind-hearted, gentle, and sensitive nature, caring deeply for others. When facing trouble, she typically relies on rescue from allies like Anpanman or calls out for her sister Rollpanna if alone. She occasionally demonstrates cleverness and enjoys spending time with the dog companion, Cheese.

Melonpanna wears a dark green uniform with a light green belt, gloves, and shoes, complemented by a cape featuring green on top and orange underneath. Her distinctive facial features include large green eyes, a small green nose, three diagonal crossing lines on her face, and two small orange hollow diamonds at the sides of her face. An insignia resembling a cursive "m" appears on her dress.

Her primary ability is the "Melo-Melo Punch," a special attack that paralyzes adversaries with affection or awakens individuals from deep sleep without causing harm. She also produces "Melo-Melo Juice," droplets squeezed from her head that cure allies affected by Baikinman's darkening tricks, though this ability has limitations in specific circumstances involving Rollpanna. Like several other heroes, she can fly.

Key relationships define her background: Rollpanna is her older sister, though they seldom meet, causing Melonpanna loneliness. Creampanda is regarded as her younger brother. She maintains an alliance with Anpanman and his team. Created by Uncle Jam, her ongoing separation from Rollpanna, who wanders alone due to her dual-hearted nature, significantly contributes to Melonpanna's character motivation and emotional state.

In "Soreike! Anpanman: Yōsei Rinrin no Himitsu" (The Secret of Fairy Rin-Rin), Melonpanna appears as part of the supporting cast.