Yuu Morisawa, a 10-year-old girl granted a magical wand by the alien Pino Pino, transforms into the 16-year-old idol Creamy Mami. Her temporary powers let her rise to stardom under Parthenon Productions, juggling her ordinary life with secret performances while hiding her identity from her childhood friend Toshio Ōtomo, who grows enamored with her glamorous persona. Navigating rivalries like the envious Megumi Ayase and resisting schemes from adversaries such as Snake Joe, she relies on the magical cats Posi and Nega to enforce ethical limits—though she sometimes bends rules, using magic for school shortcuts. When Toshio accidentally witnesses her transformation, triggering a loss of her powers, they journey to Feather Star to restore them, erasing his memories. Yet a recorded tape later reignites his suspicions, ultimately revealing her dual life.

In crossover tales, Yuu allies with magical peers like Magical Emi and Pastel Yumi to thwart threats, from monsters aging women to interstellar invasions. Spin-offs and recap films blend original footage with new scenarios, showcasing fictional commercials or communal escapades like onsen trips. Through these trials, Yuu grapples with identity, duty, and balancing personal dreams with magical demands. Her arc culminates in Toshio embracing her true self, dissolving their romantic tension and cementing her evolution from an uncertain child to a confident figure mastering both mundane and extraordinary worlds.