Hazuki Toreishi is the mother and manager of the five Toreishi sisters, who comprise the idol group and fighter pilot squadron called the Hummingbirds. Her father, a wealthy businessman, founded the company that designed and built the specialized combat aircraft flown by her daughters. She leverages this family background and inherited business acumen in her professional duties.

As the Hummingbirds' manager, Hazuki manages contract negotiations with entities like the Japanese Air Force and oversees the group's business operations. She also serves as the primary songwriter for their musical career. Acting as the liaison between the Air Force and the team, she ensures operational coordination and fulfills command duties, positioning her as the squadron's de facto commanding officer. Her eldest daughter, Kanna, functions as the executive officer responsible for tactical execution and contractual compliance.

Hazuki's family consists of her five daughters—Kanna, Yayoi, Satsuki, Uzuki, and Mina—alongside her father, Bun Toreishi, who supervised the aircraft design, and her husband, Yuma Toreishi. Yuma, a fighter pilot, disappeared during a flight mission and is presumed dead. Her leadership necessitates balancing familial bonds with the professional demands of the Hummingbirds' dual careers as idol singers and combat pilots.