Mindy Asuka, originally named Momoko Asuka, was born in Japan on May 6, 1990. Her family moved frequently due to her father Kenzo's career as an architect and her mother Minori's work as a photographer. She spent significant childhood years in New York City, where language barriers and social isolation initially challenged her. During this time, she befriended an elderly bakery owner, Majo Monroe (sometimes called "Mamie Gâteau"), who taught her English and baking. This helped Mindy adapt to American life and form friendships, including a close bond with Beth.

Discovering Majo Monroe's identity as a witch triggered a curse transforming the woman into a witch frog. Guilt drove Mindy to become a witch apprentice to reverse it. She successfully obtained her crystal ball—a yellow three-leaf clover—but Majo Monroe passed away soon after, leaving Mindy a red earring as a final gift. In grief, Mindy attempted forbidden magic to resurrect her, shattering the crystal ball and losing her witch status. This compounded her trauma, especially after her family returned to Japan, where she again faced language difficulties and isolation.

Reintroduced as a witch apprentice by the Witch Queen, Mindy joined Doremi Harukaze and her friends to manage the transformed bakery, Maho-do. Initial reserve stemmed from language limitations and unresolved grief, but she gradually revealed an energetic, optimistic personality. She shared Doremi's enthusiasm and occasional airheadedness, yet was more emotionally expressive and academically diligent, achieving grades comparable to Hazuki Fujiwara's. She enjoyed baking, sports, and reading. Mindy passionately advocated for peace and liberal ideals, sometimes adopting hippie-inspired attire during these expressions. Heightened emotions occasionally led to stubbornness or excitability, causing her to lapse into English.

Physically, Mindy was the tallest among her peers, with fair skin, distinctive lime-green eyes lacking detailed pupils, and long citrine-blonde hair in looped braids secured by lavender accessories. A teal-green clip held her bangs and face-framing strands. Her signature outfit featured a cropped orange shirt, a white skirt with a yellow side slit, yellow suspenders, black socks, and white sneakers with yellow laces. She consistently wore the red earring from Majo Monroe, defying school rules to keep it. Her witch transformation involved a yellow-themed costume, activated by the incantation "Puritii Wiichi Momoko-chi!" ("Pretty Witch Momoko-chi!"). Her spells included "Perutan Petton Palalila Pon!" for magic and "Perutan Petton Sawayakani!" for the magical stage. Her fairy companion was Nini (Dydy in some sources), who communicated in English.

Mindy's relationships evolved significantly. She bonded with Doremi over shared exuberance and their shared classroom. Her bluntness initially caused friction with Hazuki and Onpu Segawa before reconciliation. She developed a supportive friendship with Elena Tamaki after understanding her struggles with loneliness and a rival named Mary. Maternal instincts grew while caring for Hana-chan (Flora), initially challenging due to inexperience. After accidentally making Flora ill, Mindy diligently nursed her back to health, later helping cure her "vegetable curse" by baking vegetable-infused cakes. She also shared a secret spot with Hazuki and encouraged Kotaro Okajima's kendo pursuits, gifting him a kiss for motivation.

Her character arc centered on processing grief and rebuilding connections. She slowly accepted Majo Monroe's death while honoring her legacy through baking. By the series' conclusion, she faced a choice between staying in Japan with her friends or moving back to America with her parents. She chose the latter, intending to reopen Majo Monroe's bakery in New York while maintaining her witch identity and long-distance friendships.