Sumire Kasugano is one of Sally's first human friends on Earth. She possesses a distinctly girly personality, displaying feminine mannerisms and interests that contrast with Yoshiko Hanamura's tomboyish nature, establishing an early character dynamic archetype.

Sally rescued Sumire and Yoshiko during a burglary threat at a department store, leading to their meeting. Unaware of Sally's magic or origins as a witch princess during their initial friendship, Sumire quickly bonded with Sally, becoming one of her closest companions. She attends the same elementary school as Sally and Yoshiko, participating in their daily activities and adventures.

Sumire consistently serves as a supportive friend throughout the series, involved in the everyday escapades and lighthearted mischief surrounding Sally's life on Earth. She provides a human perspective as Sally navigates concealing her magical identity. Her narrative culminates in the original series finale when she witnesses Sally using magic to extinguish a school fire, directly causing Sally's necessary departure back to the Magic Kingdom.

Years later, in the sequel series *Sally the Witch 2*, an older Sumire reappears. She reunites with Sally upon Sally's return to the human world, resuming their friendship and participating in new magical adventures, connecting the sequel to the original storyline's foundational relationships.