Melonpanna, crafted by Uncle Jam from melon bread, bears a crisscross head pattern and a cursive "m" insignia on her uniform. Her appearance features large green eyes, a light and dark green outfit with a green-and-orange cape, and distinctive orange diamond markings on her face. She stands shorter than most main characters yet taller than Akachanman and Creampanda.

Gentle, kind-hearted, and sensitive by nature, she displays courage when necessary. Though possessing super strength, she avoids violence, fighting only in dire situations. Her core motivation stems from profound devotion to her older sister, Rollpanna, whom she adores intensely but rarely sees, fueling persistent loneliness and strong reactions to separation.

Her signature "Melo-Melo Punch" pacifies foes by inducing affectionate paralysis or euphoria, neutralizing threats or awakening sleepers. From her head, she secretes "Melo-Melo Juice," droplets curing allies darkened by Baikinman—though its power wanes if Rollpanna’s "good heart" falters. Like Anpanman’s core allies, she can fly.

During Rollpanna’s creation, Melonpanna added her melon juice to the dough, hoping for a devoted sister. Baikinman sabotaged this by infusing an evil "Baikin plant," splitting Rollpanna’s heart into good and evil halves. Rollpanna’s evil side emerges near Anpanman, while Melonpanna’s presence typically restores her goodness, positioning Melonpanna as Rollpanna’s primary stabilizer during rampages.

Beyond her sister, Melonpanna maternally protects foster sibling Creampanda and stands as a steadfast ally to Anpanman, Cheese, and other heroes. Despite occasionally requiring rescue, her emotional resilience and unique abilities prove vital in resolving conflicts involving Rollpanna or Baikinman. Her design and personality draw loose inspiration from heroines like Gerda ("The Snow Queen") and Candice "Candy" White Adley ("Candy Candy"), emphasizing innocence and determination.