Melonpanna originates from melon bread crafted by Uncle Jam, standing as one of the core heroic figures in the Anpanman universe. She sports a dark green uniform accented with light green details, including gloves, boots, and a belt. A cursive "m" insignia marks her chest, while her face features three diagonal crossing lines, large green eyes, a small green nose, and orange diamond-shaped cheeks. Her appearance is completed by a cape with a green exterior and orange underside.

Her personality centers on kindness and gentleness, yet she possesses latent super strength. While avoiding confrontation, she will use force to protect others or counter significant threats. A recurring trait is her profound loneliness and longing for her older sister, Rollpanna, whom she rarely sees. This emotional connection deeply influences her actions and decisions.

Melonpanna's primary ability is the Melo-Melo Punch, which pacifies adversaries by inducing affectionate dizziness or paralysis without causing injury. This punch can also awaken individuals from deep sleep states. Her secondary power, Melo-Melo Juice, involves extracting droplets of melon juice from her head. This juice reverses the effects of Baikinman's "blackening" corruption on allies, though its efficacy diminishes if Rollpanna's pure heart energy falters. Like other flying heroes, she gains flight when wearing her cape.

Her relationships define key narrative aspects. She shares a deep bond with Rollpanna, whom she persistently regards as her sister despite Rollpanna's struggles with a dual heart (one good, one evil). Melonpanna's presence often triggers Rollpanna's good heart, acting as a stabilizing influence. She maintains a sibling-like connection with Anpanman, who treats her as a younger sister figure. Creampanda is considered her foster younger sibling, reflecting a protective dynamic. Her ties extend to Uncle Jam, Butterko, and Cheese the dog, whom she involves in activities like attending performances.

Her background involves indirect involvement in Rollpanna's creation. Melonpanna contributed her melon juice to Rollpanna's dough alongside the "Flower of Pure Heart," intended to instill kindness. Baikinman's sabotage with a "Baikin Plant" resulted in Rollpanna's dual nature, complicating their relationship. Melonpanna's persistence in seeking closeness sometimes strains interactions, occasionally pressuring Rollpanna to abandon personal opportunities.

Across media, such as the film *Omocha no Hoshi no Nanda to Runda*, she participates in team missions while remaining focused on aiding allies and navigating her sisterly ties. Her character consistently emphasizes compassion and familial loyalty.