Hana Ginji is a young elementary school student who serves as a genius engineer and the primary creator of the magical brooms used by Magilumiere Co. Ltd.. Her background is rooted in a family of scientists, and her exceptional intellectual abilities were recognized at a very young age, leading to her training by her father, who also acts as her assistant. Despite her age, she is a trusted technician personally endorsed as a reliable person by company leadership, and all the brooms utilized at Magilumiere were developed by her.

In terms of personality, Ginji is defined by her immense intelligence and an all-consuming passion for her work. She is considered an engineering prodigy, often spending sleepless nights designing and improving her broom creations due to her deep affection for engineering. When she becomes excited by a new idea or a person's unique talent, she tends to hyper-focus on her work, ignoring advice and treating her assistant as a gofer. Despite her professional confidence, she can become nervous in certain social situations, such as when interacting with the programmer Kazuo Nikoyama, for whom she has developed a notable admiration that borders on a crush. Her primary motivation is her love for invention and improvement, constantly seeking to push the boundaries of her magical tools. She is particularly intrigued by Kana Sakuragi, whose exceptional ability to memorize and meticulously follow instruction manuals inspires Ginji to want to create new brooms and push her own designs further.

Within the story, Ginji plays the crucial role of the equipment developer and maintainer for the magical girl team. While not an official employee of the company, she frequently handles the maintenance and upgrading of the team's brooms. Her role is vital as she tailors the magical tools to the specific needs and fighting styles of the users, such as making Hitomi Koshigaya's broom lighter for easier handling. She is also shown observing field operations to collect data, demonstrating a vested interest in how her creations perform in real-world combat situations.

Ginji has several key relationships that define her interactions. With Hitomi Koshigaya, she shares a warm rapport, calling her big sis and understanding her personality well enough to customize her broom for ease of use. She holds Kazuo Nikoyama in high regard for his programming skills, a respect that has developed into a more personal affection, to the point where her assistant uses Nikoyama's voice to wake her. Her relationship with Kana Sakuragi is built on professional admiration, as she greatly values Kana's talent for data retention and her reliable use of the broom's complex features. She also works alongside the researcher Iroha Akasaka, with whom she collaborates due to their shared engineering-focused mindset. Her assistant, Nishina, a former government engineer, is completely dedicated to her, having become enamored with her talent and serving her needs.

Throughout her appearances, Ginji shows development by becoming more directly involved with the team she supports. Her notable abilities lie entirely in her technical and engineering genius, specifically in the creation, tuning, and upgrading of magical brooms. She is capable of designing complex features like code input systems for scanning and developing energy-saving models, proving her ability to innovate beyond standard adjustments. Her excitement for her craft and her capacity to translate a magical girl's potential into functional equipment are her most defining characteristics.