Bibi Harukaze, nicknamed Pop Harukaze, is the younger sister of Doremi Harukaze. She possesses fair skin, red-pink eyes, and shoulder-length pink hair arranged in two wing-like buns secured with scrunchies, complemented by side-swept bangs. Her initial attire includes a lavender long-sleeved blouse with white buttons, a wine-colored skirt, pale pink socks, and blue shoes adorned with purple balls. Later, she transitions to a sky-blue puff-sleeved shirt featuring a white collar and thin white bow, maintaining the purple skirt and socks while switching to white-laced blue sneakers. As a witch apprentice, her uniform incorporates red tones, and her crystal ball is red and clover-shaped.

Bibi initially exhibits maturity beyond her years, displaying responsibility and cleverness that contrast with her sister. Popular and viewed as a leader among kindergarten peers, she harbors early resentment toward Doremi, criticizing her academic struggles and social life—partly fueled by jealousy over their mother teaching piano exclusively to Doremi. Despite frequent teasing and conflicts, Bibi deeply cares for her sister and gradually softens her attitude. She experiences jealousy when Hana gains attention but learns to embrace childhood imperfection over relentless perfectionism, eventually acknowledging shared traits with Doremi and valuing their sibling bond.

Bibi becomes a witch apprentice after accidentally discovering Doremi, Hazuki, and Aiko using magic at MAHO-Dō. To safeguard their secret, Majo Rika offers her apprenticeship. Though her initial motivation mirrors Doremi’s, Bibi struggles with nocturnal witch exams due to deep sleep, often missing them despite attempts to stay awake. She later passes by demonstrating skilled magic during a magical milk wave incident, earning a fused trumpet-pollon and fairy partner Fafa. Unlike older apprentices, she serves as Hana’s "big sister" rather than a maternal figure. In Dokkān!, she tutors Hana academically when Hana struggles with human schooling due to her young mental age. Bibi also temporarily manages MAHO-Dō in Mōtto!, showcasing strong salesmanship.

Her strained relationship with Doremi originates in early childhood: as a baby, Bibi enjoyed time with Doremi, who rejected her out of jealousy over parental attention. Their dynamic improves after both become witch apprentices, fostering mutual understanding. Family life includes parents Keisuke (a journalist) and Haruka (a former pianist), with occasional home disputes. By the series’ end, Bibi confronts a choice between becoming a full witch—gaining longevity but separating from her family—or remaining human. This unresolved decision reflects her journey toward self-determination beyond merely following Doremi.