Maisy is Kurt's granddaughter and lives in Azalea Town in Johto. She shows up across the games, anime, and Pokémon Adventures manga.
In the anime, she helped Ash, Brock, and Misty gather Apricorns to craft custom Poké Balls.
In the Pokémon Adventures manga, things get more dramatic. When Gold first met her and Kurt, Maisy mentioned wanting a Friend Ball to catch a cute Pokémon she'd spotted in the mountains—but Kurt refused to make one for her. He was protective of his craft, explaining that his family had monopolized Poké Ball creation for generations before companies started mass-producing them. Kurt didn't think Gold had enough experience to handle his special Balls, which frustrated Gold.
Eventually Kurt relented and crafted a Friend Ball for Gold. The two of them headed into the mountains hunting for Maisy's target, a Teddiursa, but ran into trouble when a wild Ursaring showed up to protect its baby. Silver happened to be in the area after his own Ursaring using a custom Heavy Ball, and the two boys teamed up to catch the mother bear with their custom Balls. Gold handed over the Teddiursa to Maisy afterward.
Later, Maisy became a target when the Masked Man took her hostage, using her as leverage to force Kurt to surrender the design plans for the GS Ball.
Content compiled by AnimeList.moe from publicly available sources.
