Emerging from a heart-shaped mirror as a luminous fairy, Topo gains physical form by inhabiting Mai Kazuki's stuffed flying squirrel doll. As a supernatural guide, he gifts Mai a magical bracelet decorated with four card suit symbols—spade, club, diamond, and heart. This bracelet conjures a wand enabling her transformation into the teenage magician Magical Emi.

Topo mentors Mai by supporting her performances with the Magic Carat troupe through magical aid. Yet he consistently emphasizes her need to hone independent skills, reinforcing that true mastery requires personal growth beyond supernatural assistance. His guidance extends beyond spellcasting to strategic problem-solving during challenging situations.

In the OVA "Semishigure," Topo sustains his role from the television series, backing Mai's journey as the special revisits the main story and introduces fresh developments. He also appears in crossover OVAs like "Adesugata Mahou no Sannin Musume" and "Majokko Club Yoningumi A-Kukan Kara no Alien X," joining broader magical girl narratives alongside characters from other Studio Pierrot series. His characterization remains consistent across these spin-offs as Mai's steadfast magical companion.

Across all appearances, Topo functions solely as Mai's magical guide and transformation source, with his existence intrinsically dedicated to fostering her growth as a magician.