Miki Mizusawa is a friend and former mentor to Sae Sawanoguchi, living in England during the television series events. She was once a member of the Magic User's Club at Kitanohashi High School for an unspecified duration before moving abroad. Her father, based in England, is acknowledged as a "grandmaster" sorcerer, and Miki presumably trained formally in magic under his direction. This training granted her advanced magical abilities, including the capacity to fly unaided by broomsticks and the power to conjure a magical serpent for aid.

Sae keeps Miki informed through regular written correspondence, detailing the activities and challenges confronting the Magic User's Club after the Bell transforms into a giant cherry blossom tree. Primarily an off-screen confidante and advisor, Miki offers Sae a distant yet supportive presence via these letters. Her grasp of magic and previous club connection provides Sae a link to more established magical traditions.

Miki appears exclusively within the television series continuity and does not feature in the original OVA series, any films, spin-offs, or other official franchise extensions. Her background as the daughter of a prominent sorcerer and her own developed magical skills position her as a figure representing higher magical expertise compared to the high school club members, though her direct narrative involvement remains confined to her epistolary relationship with Sae.