Patina, originally Majo Rika, operates the Maho-do magic shop. She hails from the Witch World, born according to lore from flowers in the Witch Queen's garden. Raised by the elderly witch Majo Ririka, whom she affectionately calls "Mama Rika," she formed a close adoptive bond. Her youth featured a fierce rivalry with Majo Ruka, later revealed as her twin sister; their conflicts frequently centered on competing for ownership of the Maho-do in Misora City.

Exposure as a witch by a human girl transformed her into a green, frog-like creature possessing a single curled strand of hair, black button eyes, and a purple sphere on her neck. In this form, she typically dons a witch hat and shawl for travel. Her original witch appearance was that of an elderly woman with gentle red eyes, minor wrinkles, dark green hair styled in large oval buns featuring a forehead curl, dark green clothing with an indigo-shaded cape, and her signature purple crystal ball. Her personality is choleric; she often appears grumpy and cantankerous, easily angered by incompetence or disruptions. Strongly greedy, she frequently prioritizes profit and self-interest, struggling to admit faults or express vulnerability due to pride. Yet, she possesses a hidden capacity for kindness, particularly toward her witch apprentices, whom she gradually views as surrogate daughters.

Her magical abilities include infusing enchanted items with strands of her hair and casting spells despite her transformed state. Her primary companion is her fairy, Lala, who can assume the form of a white cat in the human world; Lala teases her constantly, though mutual care underlies their dynamic. After her transformation, she mentors multiple witch apprentices—initially to regain her form but later out of genuine investment in their growth. Her relationship with the girls evolves from initial resentment and frequent bickering, especially with the main protagonist, into dependence and subtle encouragement. She demonstrates specific bonds: valuing one for business acumen, another for diligence, and comforting the youngest during distress. She also acts as a secondary caregiver to Hana-chan, a witch baby the apprentices raise.

Her development includes reconciling with Majo Ruka, transitioning from bitter rivals to companions who socialize. She expresses deep attachment to the Maho-do, experiencing depression when faced with separation. By the final story arcs, she actively participates in resolving larger conflicts, aiding efforts to heal a cursed forest and supporting the protagonists during Hana-chan's maturation. In the conclusion, she returns Hana-chan to the Witch World, symbolizing her role in closing the apprentices' journey. Supplementary media like the OVA series *Ojamajo Doremi Na-i-sho*, set during the main timeline, explore minor secrets and daily interactions.